ok so i race SC class. I'm looking to get into 1/8th scale eventually. Can I use the speed control from an 1/8th scale in my hpi blitz then when i bump up to a bigger race class just move my ESC over and get a new motor? I guess what i'm asking is will an 1/8th scale speed control run a 1/10th scale motor?

That should work fine using a 1/8th esc to run a 1/10th. Its the other way around that would have probs. Good plan, thinking ahead!