RE: Sidewinder vs. Mamba Micro Pro
i would guess it would be more features as well as handle more amperage, as the sidewinder is to the mamba max. as for motors, i have the 8000 (mamba 25 esc) and on 6 cells its pretty darn fast. it kind of depends what you're doing. unless you're looking for speed runs, i think the 6800 would be better for a shorter track. for an extra $20 it might be worth while to go to the pro. with the discount its really only like a 10 dollar difference.
what will you be doing with the truck by the way?
oh yeah and i've heard castles customer service is awesome, so you could always call or e-mail and i'm sure they'd be happy to answer any questions.