Im just now considering doing 4s for my speed runs in my rustler. I have found 2 2s packs that would cost less than a comparable 3s in terms of discharge. It'd be alot more economical for me to purchase 2 2s packs that I can run in my rustler,stampede,xxx-t than to waste alot of money on one 3s pack that will only get used for speed runs. I already have the CCBEC installed,red wire removed and fan on esc for the hell of it. The only difference is Im not running some low kv/ high effecient motor. I'm running a current hoggin 6900. Is there like a certain range of watts that the esc starts not liking? I'm not sure how many amps the 6900 will be pulling, but couple that with the increased voltage, I'm sure it will be hard on the esc. Im not worried about the motor at all, if that goes, oh well, I'll get a 9000 and start over again :P But I am worried about my esc, I wouldn't want to smoke that.