Could I get the 10S ESC and run it on 5S with the HobbyCity motor for a while then a CC Neu? I'm just a little worried about getting a MMM because I've heard of a few people frying them for no apparent reason. (Even the v3 ones)
You could, but it is better to do it right the first time. Although, if it's going to take you a year to get the components together, get something cheap to throw in there.