I'm running that setup on my E-maxx right now. Geared 58/20 and not having any cogging issues unless I try going about 1/2 MPH. It's topping out in the 40MPH neighborhood. Only problem I have is that it is constantly pulling wheelies.
As long as you have the external BEC I can't see you having any issues. I haven't gotten a fan for mine yet but as long as I'm not in the grass I'm not having heat issues either, will be adding a fan very soon though.