This plane is designed for 3D flight. that said, don't fly it fast buddy or it'll come down on ya and you could end up with a mess. the control surfaces on this plane are too large for speed flight. they will flutter and could potentially come off in flight... no control surfaces, no control, i'm sure you know what happens next.
Yes, everyone is putting a bigger engine in this plane than what was recommended by Great Planes. They make great planes but their assesment as to the appropriate size of an engine for this plane was way off. The maximum 2 strok recommended is a .50. Sure a .46 and .50 will fly it but don't plan on having much power for take off's, or any stunts for that matter. So you did right with your engine combination. I've read that the Saito 82 is perfect for this plane. 13 x 4 wide size prop sounds like that favorite out there. or 13 x 5 regular width prop. that's what I'm running with a .61 fx and it's great.
Glad to see that you love this plane. It love it too.