I think early in the series he was also making the myth of the Forsaken seem bigger. Personally I think he was using the theme of time changing perception "fades into myth and myth to legend" and all that when he originally spoke about the Forsaken strength (i.e. 10x an "average" Aes Sedai), but as the series progressed this clearly became a legendary view of the OP strength rather than a credible estimate. Even later in the series Egwene thinks that linked with Romanda and Lelaine she couldn't face a male Forsaken, which I think has clearly been shown as inaccurate in terms of simple strength measures. Perhaps the use of the True Power during the AoL enhanced the perception of the strength of the Forsaken. But with the loss of the knowledge of the True Power in society the myth became about OP strength.

At this point I think we can guestimate that level ++1 is probably in the range of 20% stronger than level 1 which is probably about 20% stronger than level 8 which in turn is around 20% stronger than level 13 ... but I think it's fairly accurate to say that the ++1 men are roughly 6x the weakest Aes Sedai levels and the 1 women are probably 5x the weakest Aes Sedai levels ... we know level 13 is roughly 3x the weakest Aes Sedai levels.

I guess it's a matter of perception now. But even after RJ started dropping power levels in every other sentence I never really got the impression that the Forsaken levels were vastly higher than the top Aes Sedai, it always seemed to come down to skill, training and knowledge of how to use the OP to me.