I have been working on deciding which system would best represent the power of channeling in Wheel of Time. D20 just does not have what is needed to do the job and there are several reasons why.

1. No way to show the channelers strength with individual flows
2. Talents have to be feats which just strikes me as wrong
3. To be honest, channelers that are not exceptionally weak (Morgase) can mop the floor with a non-channeler who does not get the drop on them. Yes it isn't balanced, but life isn't fair.
4. Magic in D20 is too codified. One thing that is made very apparent is that the One Power is near limitless in what it can do. D20 does not support this kind of magic at all.

It is for those reasons that I have been trying to find a system to create a WoT game for a few years now and after much debate have settled on the L5R 3rd Edition System. Let me list the reasons why.

1. You are able to have characters be strong in one flow because the 5 flows are all represented in the characters stats (Earth, Air, Water, Fire, and Void for Spirit).
2. Talents can be advantages and as an added plus if you want a character who is bad with a specific flow (a male not able to use water well for example) you can have disadvantages to show that.
3. Combat in the system is DEADLY. Also you don't have the my turn takes 30 minutes effect that 3rd edition D&D had (4th fixed this thankfully).
4. The magic system in the book supports free forming. As the DM you just have to find out A. What the channeler is wanting to do, B. Tell the channeler what flows that uses and C. Tell them how many successes they need on their check to pull it off.

Anyway, I highly recommend avoiding D20 for a Wheel of Time based game. It cannot represent things properly IMO.