Yes, the NiMhs are prob big enough to need 2 passes thru your charger - just watch temps- especially on the 2nd pass. They should not get so hot that you can't hold them. When they peak on a peak charger, they are 1250135F, so they do get hot, but you can still hold them. ABove that, you're damaing the cells.

Your esc should just be doing what the motor is telling it - unless you have installed a motor that is below the turn limit for that esc - then you will have probs and may burn the esc up. That esc is supposed to be good down to 10T, so I don't think esc is a prob.

Try the NiMhs after 2 passes thru charger (watch temps!!) and see what that runs like.