running lower rpm?

[lincpimp]

And the hacker c50 motors are fine at 45k max rpm, maybe more.

I would say that the 16t pinion in the lsp would be a good place to start. I always gear for mid 30s for first tests and then gear up until I am happy with performance.

The 10l was running at a good rpm, according to the temps. You most likely had too much load on the mega, that was causing the heat issue with the esc, and most likely a big voltage drop. Better batteries may help, but the low motor rpm and steep gearing will produce more heat in any case.