David,

I do agree with you about AX. based on my experience on a great planes Easy sport MK 2 the AX engines will provide slightly more power than FX series, after it crashed I changed the .46 Fx with a FX.
Though the repair procedure made my plane heavier but it flew even more powerful.
and about the RF and SF engines I think I was in a big mistake till now.
Thank you for sharing your knowledge.

Ehsan