I'm having trouble understanding your interpretation of the "Nynaeve would do better still" argument.
We have two options:
1)Angreal are multipliers: So Elayne's strength gets multiplied by X, and this happens to be twice Nynaeve's strength. For Nynaeve herself, of course, multiplying her strength by X would mean access to even more of the OP.
2) Angreal are additive: there's a lot going for this, especially based on what we know about Seeds now. If so, Elayne's level+X is twice Nynaeve's strength. Obviously, Nynaeve herself would do better if X were added to her greater strength.
In neither scenario do we have to assume that angreal somehow work differently based on your strength. They either add or multiply, and they do so evenly for all channelers.
Multiplier model makes the bracelet vastly too powerful for Rand to have had any chance on the docks. For it to have made Moiraine stronger than her previous level it would have needed to multiplied her new strength by at least 6x (possibly more), but that would have made Lanfear like 5x Rands strength on the docks which seems like a lot even with the fat man angreal. Especially since she had the bracelet before he drew through his angreal.
Additive model has flaws as well,as I mentioned in my earlier post that it doesn't fully explain how the Turtle could make Elayne 2x Nynaeve and still be a "weak" angreal, in fact it would likely be stronger than the bracelet given what we know it will make Moiraine stronger than level 13 but seems unlikely that she would be much beyond that from the way it's phrased.
Perhaps there are both multipliers and additive angreal.