Here's a quote from the Flightpower website:
"Fast charge rates up to 3C approved in conjunction with balancing, the FlightPower V-Balance is ideally suited."
These must have some superior chemistry to support a 3C charge rate.
A 2S2P 6400mah pack could be charged at 19.2 amps!
We're talking some FAST recharge times at that rate.
I'll probably just "play it safe" at 5 amps though.