Hello; I have been flying my 4*60 for a few years now (maybe three) with an old OS90 4 stroke, and am very happy with it. Another fellow at our field flys a 4*120 with a super tigre 90, that also works great. I love that huge prop and teh things I can do because of it. The fellow with the 4*120 zooms around at full throttle all the time, and can't be convinced to throttle back and enjoy the slower speed handling. I don't know really how that plane handles except at high speed. The ST 90 does that pretty well, I don't know if that engine won't run cleanly at lower revs. I suppose if you want to scoot around and never attempt low speed handling, I suppose a big two stroke will do that. I p[refer the four stroke myself, I enjoy flying at the slow end oof the flight spectrum.