We are presently flying a 11Lb 1280 sq in model with a 40RE and pipe - this power/ weight combo is very fun!
When you get into this 20 oz ft realm -and swinging BIG props - it is competely different
I am using trimmed 22x12 props and 20 10 stuff -
We also took it to the TOC and some of the guys flew it on Monday --
Tunnel vision is sticking with HEAVY arfs---get out the sticks and glue -then your new engine will really be a blast.