I have just added the foam stiffeners along the fuselage from nose to tail. It holds the tail a lot better than bracing and it makes the whole plane a lot stiffer.
I took it outside for a quick test flight and the maneuvers are a lot more solid. Specialy snap rolls and rolling harriers where I could see the plane hesitating sometimes and I had to correct it with control inputs. Now the plane rolls on its own, without the need of any correction. Next step is to add CF to the TE.
I may work on the plans tonite.