Yeah, for run-of-the-mill non-3D flying an OS 160 is the way to go. The CG is right on and the engine is the most reliable I have ever used. I flip start the 160, and only have had a rough time once or twice (not primed enough).

Go with a top of the line 40 to 50cc engine (lightest possible) if you go gas, but I wouldn't recommend it.

Good luck.