Don't worry about the ESC unless you can step up to something like the Castle Mamba X. The stock ESC is a re-brand of the Hobbywingok. that makes sense. would getting a different esc help with that. bah. i don't know if i need to get this deep into the hobby. well, if it will bring memories with my son, then shoot for the moon i suppose.
Max10 line, and those are pretty good. Max10 would get you more programing options, but the same basic ESC "Engine". But, neither will help much with runtime (much).