A few issues to cover, so I will break them down per heading. Let's start with:

The Aviendha quote:

This is a rather interesting point. If you say that being able to "overcome" Amys and Melaine combined is different from being as strong as the two combined, then it seems pretty clear that the ability to DO things with the Power does not increase in linear fashion as one goes up the list. In other words, while the strength list may be linear, this quote makes it rather obvious that one's actual capability to affect the physical world increases in some different formula to your strength on the linear list. Maybe it is cubic, for example. Much like the Warp Drive scale in Star Trek.

For example, Warp 8 = 8x8x8= 512 times the speed of light, while Warp 9 =9x9x9= 729 times the speed of light. So while the scale is linear in its distribution, its actual physical impact is cubic.

Similarly, then if based on Egwene's strength only, Aviendha assesses her as capable of overcoming two powerful channelers together, despite only being 11% or so stronger than Amys according to the Companion, that tells us that One Power feats do not increase linearly with strength on the strength scale. But more on this later.

The Siuan issue:

Siuan's strength is actually critical to the integrity of the entire strength scale. Since we know that she was signficantly below half her strength after being Healed from stilling, a placing of her at almost 60% of her former strength throws out the linear nature of the list completely. It is clear that RJ intended her to be lower than half her former strength, based on the direct quote he placed in the books. The fact that the authors of the Companion got her placing at almost 60% of her former strength directly from the so called notes, calls into question the integrity of all the notes.

Clearly the notes were compiled over a long period of time. Some were updated in recent years, others he clearly never bothered to get back to, as he may have had new levels for other channelers in his mind to compensate for the changes he did make in the notes. So in short, we don't know if the changes he made to the list was complete, and whether he meant to still get around to changing everyone else after placing say Siuan at a higher level than he indicated in the books. And whether he didn't even bother updating any of the Forsaken as he knew in his own mind what their new levels were, etc. The point is, why ignore the entries for some channelers - which are clearly inaccurate - while relying on others? The whole list is suspect.

Logain's strength and the gender of shielders:

Here we have a real dillemma for the Companion. It is the Aes Sedai themselves who state that Logain might have been able to break free if only 5 of them were holding the shield. They know this because they directly felt the pressure he was exerting when trying to break free from 6. So clearly, Logain's strength comes very close to being able to break free from 5 Aes Sedai.

Now, it is interesting that you assert that Shielding someone of the opposite sex is much more difficult, (which we know of course), without extending the same allowance when it is males shielding females. And we have a very good example of just such a situation. I am talking, of course, about when Rand shields both Egwene and Elayne at the same time, while weaving about 10 additional weaves simultaneously.

So according to the sortable list based on the Companion itself, Egwene was supposedly a level 12 at this time, while Elayne was a level 35. Let me start by saying that I question these low ratings for both women at the time, as Egwene appeared significantly stronger than Moiraine even then, having been forced by the Seanchan, so placing her at level 12 is an absolute minimum and frankly, inaccurate in my view. Similarly Elayne, who is suggested to have gone from a paltry level 35 to a level 17 between the start and end of Shadow Rising. That is a whopping 58% increase in one book, despite no forcing taking place. That is not how female strength increases. Instead, it increases gradually, not in jumps.

Nevertheless, even though I disagree with the low estimates for Egwene and Elayne at the start of tSR, I will go with it, to illustrate the inconsistency of the way inter-gender shielding is treated in your approach. So with Egwene and Elayne at levels 12 and 35 respetively, that places them, according to the linear list, at 82% at 47% of the maximum strength respectively.

Together, that makes them 129% as strong as Lanfear at that point in time. So I ask you, if it is much more difficult to shield someone of the opposite sex, as Jordan has indeed stated, then how is it possible for Rand to hold shields on TWO females at the same time, who have a combined strength significantly in excess of his own? This while still managing 10 additional weaves at the same time?

To make matters worse, this is not Rand at Lews Therin's strength level. This is a Rand who only by the end of tSR matches Asmodean, who is a level 3. So if everyone else is growing so rapidly during the course of tSR, then Rand, who is channeling constantly during that book, likely did quite a bit of growing himself before facing Asmodean. Therefore, at the time when he manhandled Egwene and Elayne, he was likely a couple of levels lower than that. Probably a level 5 or thereabouts. Remember, this is when he cannot even grasp the Source every time he tries to. Something that even Elayne can do consistently at that point in time.

So I come back to the point, which is that if 5 female Aes Sedai need to significantly exceed the strength of a male to hold a shield on him, then the same must apply to a male who tries to hold a shield on a female, let along on two females. In fact, Egwene on her own, at level 12, would have been at 81% of Lanfear's strength at the time. Therefore she would have been at an even higher proportion of Rand's untrained strength at that time, according to the Companion that is. He should not even have been able to hold a shield on her alone, going by the inter-gender shielding difficulty theory, let alone be able to shield Elayne and handle 10 other weaves as well.

The only way this can make sense, is if Egwene is not that close to Rand's level in strength, and is in fact below half his strength at the time.

Egwene's strength compared to a male Forsaken:

This point ended up being addressed by my above post, but clearly, the Companion has a major problem here, if it is to remain consistent with the books.

The gender of people holding shields:

This point too was addressed under point 3 above. To be clear, I don't have a problem with the idea that it is more difficult to shield people of the opposite sex. It has in fact long been known. Ever since RJ's own quote on the matter, which you kindly referenced again in your post. But as is shown in Rand's interaction with Egwene and Elayne, this actually strengthens the case for the top Tier Forsaken level to be farther removed from Egwene's level.

The plan for Rahvin, Graendal and Lanfear to take Rand together:

This is explained nicely by the fact that, as Rand stated, to cut him off once he already holds the Source, you need to exceed at least 200% of his strength. Two Forsaken together could not do it. But 3 could. And they obviously wanted to be sure of being able to do so. This ties in with Asmodean's quote, that 13 Daigian's should be able to do so to Rand too. To be fair, Daigian is exceptionally weak for an Aes Sedai, and given Asmodean's limited knowledge of exact Aes Sedai strengths, he might well have been talking about women slightly stronger than Daigian. But even if we use Daigian, for the sake of argument, then 13 Daigians need to exceed around 200% of Rand's strength. Meaning each one needs to be around 15% as strong as Rand.

Since Moiraine and Elaida, according to the Companion itself are around 2.57 times Daigian's strength (backed up by Leane's quote that she was less than half her former strength, but still stronger than Daigian), that would place Moiraine and Elaida at around 40% of Rand's strength, with the average Aes Sedai at around 30%. If we then take Aviendha's quote regarding Amys and Melaine as a slight exxageration (which is different from discounting it entirely, as the Companion does) Egwene at around 50% stronger than Moiraine makes sense. Placing Egwene at 60% of Rand's strength.

To conclude, I can maybe consider an explanation that at the time of tSR Jordan intended a greater gap between the Forsaken and other channelers, and that this changed over time. But this change could not have happened before Winter's Heart, given all the evidence that continued to support this picture up to that point.

Even Demandred's encounter at the Cleansing only makes sense if the two Aes Sedai and Flinn were each around 30% as strong as himself. While Lanfear noted that Alivia was stronger than herself, Demandred noted that the mixed circle led by Flinn hit his web as hard as his own spinning would. This was mixed gender circle, which increases effectiveness, and the implication was that it matched his own effective strength. Anyway, the point is that the Companion's list does not match actual events and quotes in three quarters of the series. And we know most of the last quarter was written by Sanderson, supported by team Jordan who did not understand much of what was in Jordan's head. Especially surrounding the One Power.

I'm sure I missed the odd point, which I would be happy to get back to should you wish me to. But the above has turned into a long post in itself, and I find that the more points and quotes one tries to cover in a single post, the more the important stuff gets lost in the wash, while people focus on peripheral quotes that are more ambiguous. Such as the Demandred-Flinn circle encounter, which is more ambiguous than Rand's shielding of Egwene and Elayne, which is clear and indisputable.

I look forward to continuing this discussion, as I must admit having Sid back has woken some of the old juices from 10 or so years back, when we started this whole thing. Let's see if we can keep it going a tad longer.