Personal experiences can vary...
But I put a 4.5 in this truck to test out the electric conversion and have yet to remove it as its running quite well on a pair of 2s2p Hyperion LCX packs. This is an old picture but you get the idea:
I keep waiting for the motor or the ESC to give me problems so I have an excuse to upgrade but so far...zero thermals and not a single other problem - and I would say this truck is heavy, certainly heavier than an e-savage and probably heavier than a converted savage. Gearing is middle of the road, not conservatively low, not aggressive on the top end.