I can't speak for the OS .46, but I can for the Evo .46. They are terrific as far a reliability. I have 3 and they are nearly trouble free. I have had only one issue and it was because of trash in the carb. I pulled the hoses off, and blew it out with a air hose and that was the end of the trouble.

I do own a OS .61 FX and it is terrific, also. Maybe a little more tempermental that the Evo .61 I have. The per formancebetween the OS .61 and the Evo .61 seems to be about the same. It's hard to tell.

Based on my experience with the Evo's, I would choose them due to the difference in price. The OS's may be a little more powerful, but I sport fly (am just past solo) and so the marginal possible difference would make no difference to me.