Opinions are like butholes, everyone has one and they usually stink. Well, here's mine. I have owned supertigre .51,.61 and 2300, thundertiger.46and .61, os .40 and .61 and magnum .40 2Strokes as well as OS70surpass, magnum 91FS, saito 1.00 and 1.80, and YS 1.10. Everyone of them has had thier tempermental moments and everyone of them has run absolutely fantastic. Engine choice for me is generally determined by application. If i want to scream across the sky at a thousand mph I'll run a 2 stroke. If i want to slow down and still have power to pull vertical into space I'll run a 4 stroke. I prefer 4Stroke for 3D and 2 stroke for some fun old sport flying. Which brand I buy is generally determined by how much money mama will let me spend. All the info in this thread is very good. I think you'll just have to experience both and form your own opinions.