RE: Extra 300s 40 ARF
Great plane. Mine has a Saito 91 on it turning a 13x8 APC. I think it is powered just right for the altitude I live at. I'd like to see what it would do at lower altitudes. It is a capable airplane. With a 91 it will easily hold knife edge and perform a one roll circle. It has enough authority to do a slow roll right after takeoff. Just watch out for the nasty tip stall. It does a great snap roll and will snap with too much elevator input. So, watch the low altitude manuevers.
I also added flying wires to the tail after hearing about some horizontal stab failures.
I was once at a fly-in and got a chance to fly someone elses 300 with the 61 FX on it. The plane with the Saito 91 was a little more alive and the throttle more responsive.