I use a vertigo CF 3mm thick disk and couldn't be happier. I hated how grabby the stock aftershock brakes were. Even my buddies with the LST2's became grabby and would bind within a gallon or so of use.
Although, running the single CF disk only worked really well with a higher torque servo (140oz or higher). I use a hitec 985MG (172oz). Total overkill, but it's water tight, fast and not terribly expensive ($70). I could probably have gotten away with a JR650M, but then it wouldn't be sealed and would be a bit slower. For $20 more, I'm glad I went the route I did.
With my setup I've been really happy. The brakes are no longer an on/off switch like stock and they don't hang/bind for no apparent reason. When I do apply the brake, it's much smoother with deceleration which I think will help in the long term with the diffs and cvd's.