A racer at my local track also is now a battery vendor (just starting). He's doing 2/3A cells and in some tests, he's actually (don't try this at home) charging the 1600 mAh 2/3A cells at 10A and trying to break them to see how harsh they can be handled. After 10 cycles, he's done pretty well with no venting. He thinks a good sweet spot for charging sub-C cells is 6A. I've been "babying" my cells and charging 4500mAh packs at 2A and 4A and really should be pushing it harder for higher race voltages. They've lasted a pretty good while and I think I need to also turn up the amps to charge higher to get more out of the older packs.