Another weak point has proved to be the tail of the fuselage. It breaks pretty easy around the line of the horizontal stab. To fix this I've glued light ply reinforcements on there also which have solved the problem.
The Four Star flies really really well. It is extremely smooth and neutrally stable. A few things I've found it won't do very well are:
1) Knife edge. It just doesn't want to hold it. A larger engine may help in my case.
2) Spin. If you can manage to get it into a spin it is really difficult to get out. I returned my 4 star to the kit stage atleast once when a friend was flying it and manged to get it to spin. Needless to say it spun right into the ground.
long time. Do not over power it or you won't be able to slow it down enough to get it on the ground. I use an OS 40 FP. I think this is just about ideal power for this plane. Maybe an OS 40 FX or other ball bearing 40 would be just perfect. But a 46 becomes to heavy and to powerful for this plane. It likes to fly on the wing, not on the engine. I use a 11x5 prop instead of the standard 10x6 for a .40 engine. This works really well and one might even want to go up to a 12x4 instead. This is not a fast plane so the extra thrust at lower speeds helps.
I've also tried using flaperons with dual aileron servos. It has no effect. You can't tell the difference in aerobatics when coupled to the elevator or when landing acting strictly as flaps. The 4 star can already be slowed down to walking speed without flaps so the flaps don't seem to add much. Just stick with one aileron servo and keep it light.
If you decide to build a 4 star. Just remember to keep it light and don't overkill the engine on it. Good luck.