I have had 50 cc planes from both mfgs. EF Yak and CARF Yak. I know you are asking about the Extra, but some observations I have come across are both are very very good flying planes. The EF seems to be a lighter build overall. The Carf came in at 17lbs and my DA50 has no trouble at all pulling it around. I don't remember how much the EF Yak weighed.
I can't speak to your engine choice, but You will be happy with either of the 2 you decide on.