I have a U CAN DO 3D with a OS 91 two stroke. It has been a very good plane. Really smooth, stable at very slow speeds and smooth easy flying on low rate settings. It tracks pretty good. However it does not roll on a straight axis very well. But I've learned to hover with it, it is my favorite plane, and I recomend it. It is the only 3D plane I've flown, so it makes it hard to compare. But I've seen other 3D planes fly along side me, and it seems mine is the smoothest and most stable at very slow speeds and flooting around. I won a contest to stay in the air the longest without the engine running. The engine will take the plane straight up and out of trouble with ease. If you get this plane, thsi engine does it well. The only other thing I see, is it is larger than than the 40 size competitors which is a big advantage with 3D flying.
Best wishes with your decision.
Marty