Yep, that's why I stuck with a 350x lol.
I have a kawa 350 big horn 2 stroke enduro motor that I'd like to throw in a 3 wheeler frame (200x, 350x, or 250r), just haven't ran across a rolller or
parts machine yet. I don't need the biggest hp or anything, just something fun to ride =). 200 was a bit too small for me, I had 2 200x's and ended up selling them in favor of the 350x. I kind of viewed it as my 250sx was almost as fast as the 200x, and it's shaft drive, so mud etc isn't a problem. Wish there was more sport models made as shaft drive. They might be heavier, but not dealing with a chain would be nice.
I don't think I have a spare frame for a 250es/sx, but another interesting build could be to throw a TRX350D engine in one of those frames. The bottom end is very similar to the 250es/sx engines, but the top end is much like the 350x. I have one of those quads just because of the top end design. It's heavy as hell, but does ok, huge difference from a 350x. 350x is typically described as it does exactly what you tell it to do, extremely controllable etc. The TRX350D is described as a tank, it steers like a tank (horrible turning radius), it's heavy as can be like a tank, heck it even rides like a tank lol. It's a true work horse full time 4x4. One I have has a bent front swing arm or frame, so could be a fun build to swap it in a 3 wheeler frame.