[starscream]

Kokam does have 20C high rate discharge packs available now but they do not have the voltage cut-off or charging benefits. The only thing I would question is using multiple FMA Lipo packs in a high voltage vehicle. The voltage cuttoff is controllered by the computer on the Lipo pack itself which connects to your controller. So if you are running more than one pack you won't be able to connect more that onne pack to teh controller.
I have a brushless Revo and a brushless 1/8 Mugen buggy and both motors/controllers run with 20 cells. In my case, I would need atleast a 22v Lipo pack. I emailed FMA and they said that they are working on a 6s Lipo pack and charger, for airplanes, that has the same charging benefits of the Scorpions. These will hopefully be available in May or June. The problem is, I don't think a 6s pack would fit on 1/8th buggy chassis.

As far as gearing goes on teh buggy, if your going to make a mistake make sure you gear the buggy too low NOT high. I fried my controller the first day I ran my Mugen. I was using a 46t spur and a 13t pinion. I ran the buggy for 10-12 minutes and the temp of the controller was over 210F and the motor was over 180F :(
I am fabricating new center diff mounts and will use a 62t spur/slipper from an ofna Dominator.

I am currently using GP2200's. They are significantly lighter than the 3300/3700's and have plenty of punch. I get over 12 minute run times which is just enough for those 12 minute mains.

Have fun with your conversion and take it to those nitros ;)