[starscream]

Serum,
The DPM connects in between the receiver and esc (9920 in my case)
The problem was that the signal was not getting from the receiver to the esc due to an issue with the DPM (signal voltage incapatibility I believe). At any rate, this issue should be addressed in new dpm's from FMA.

Sylvester
Those Kokam cells, configured at 2s4p, would be 12,800 mah so I'm not sure what you were trying to say exactly. You can't charge both packs at once though, this will require a second charger. I have two 6s chargers just for this reason.
I use the same power supply as MacII. I have to limit the charge rate to ~7.5 amps to run both chargers at the same time.
Both the 3200mah and 6400mah packs will work on the 2s charger.
For racing, I'd get the 3200's but if your looking for runtime, the 6400's will definetly do the trick.
Either way, I'd check with Mike and see if he has used his scorpians with a 9920 esc yet and let him know about this issue so he can address it when ordering packs from FMA.