I'd take a closer look at a Tekin system. I know they are expensive, but they are the cream of the crop right now. I looked at the Havoc systems when I was first going brushless, but they didn't stack up very well against the competetion as far as features goes. The Losi can handle lower turn motors and has a higher peak current rating then the Havoc.
The Xcelorin systems from Losi are better and can be had for the same price as the Havoc. I have a 13.5 system for sale actually. It is in the for sale forum. It's pretty new only about 8 hours use on it. I'm asking $150.