Thoughts on an e revo

[BrianG]

5s A123's should be fine, but might have trouble voltage-wise since some seem to be sensitive to over-volting. 4s A123s or lipos should be fine though. An 8XL can pull a decent amount of current so don't gear too aggressively. If shooting for speeds over ~35mph, I'd get a different ESC to handle the current better.

Yes, you can run any battery combo (within ESC specs) that will physically fit either single or dual.

To properly charge A123 cells, you should get a charger specifically made to charge them. That charger is for regular lipos only.