You could also consider the neu motor to go with the mamba monster ESC if you don't want to wait for the mamba motors to be released. I just bought the Novak HV Pro 4.5 system for my Revo and flm bought the 6.5 system for his E-Savage, so I'm anxious to see how they compare. I have two Novak brushless systems and two castle brushless systems, and I like them all. The castle stuff is really nice because of the way that you can prgram it from your computer and get the system dialed in EXACTLY how you want it.
The A123 batteries can take a quick charge and that's a plus. BUT, unless they've changed something in the last few days, the battery packs are going to be really heavy compared to LiPo, and that's going to be your enemy. Just something to keep in mind.