RE: Evolution 1.00 vs OS 91 FX
I'm not so sure about Evos being for guys new to larger engines, or the comment about not being made for horsepower. I have two of them and they are very powerful engines. I've owned a .46FX and the .46NT. I would put the NT up against any FX. The idea that Evos are for new guys is probably due to the limiters on the needle valves. They aren't a bad idea and are removable. I found that the NT low speed needle valve was far easier to tune and fly than the FX. Also, the NT tolerated out of tune conditions better than the FX. The FX crankcase loaded up worse than the NT.
Evolutions are well made engines. They have one thing that OS doesn't- chrome liners. I'm not sure I would get another OS if a comparable Evolution were available. They cost about right (cheaper than OS), seem more powerful, and should last longer.