Ive run w/ both. From 12 cells to 16, and 4S to 5S.
The best combo is 4S. 5S is sick amounts of power, and is only good for street driving and speed runs.
Vid
NiMh is too heavy, esp more than 14 cells.
My truck weighs just around 10 lbs. Is almost 100% stock over than conversion parts.
I spent an hour continuously driving it today, ESC was 130F max and motor was 166F max.