For CG, I found that 6" to be best. 6.25 is too much aft, as the plane will pitch up at inverted, and will pitch up momentarily when you slow down. Also, pitch and yaw tend to overshoot at this CG setting.

This plane is the best flat spin plane I've ever own. I'd imagine with more power, it could do a hovering flat spin. I will see if flaperon will help too.

Waterfall is really nice with full down elevator and coupled full up flap.

I really think you would enjoy it better if you have more power than Webra 91. I am not satisfied w/ the power that Surpass III 120 P provides. I tried 16x4W @ 9400 and APC 17x6 @ 8500, and both setup leave me wanting more. I will try a APC 16x6 to see if it's better. I plan to put back the Enya 155.