I've ridden some damn fast 200x's (including one raced proffesionally by a local guy that actually BEAT Curtis Sparks once). That said, never have I ridden one that will beat even a stock water cooled 250r. Even "The Man" (Sparks himself) admits his 200x won't beat an R except for maybe right off the line.
However, I would put a couple of the ones I rode up against a stock 400ex. My money would be on the 200x all the way. The one I built was pretty decent too but I wouldn't bet on that one. Even with my mods my buddies 350x would beat me pretty handily. My bike was but a shadow of the one that beat Sparks though. Not even close. At the time the only trike I had ever ridden that could beat that one were the 250r's.
All that said, I wouldn't spend my money on a powroll kit, personally. I'm sure they're nice and if you have the cash to throw around, why not. But for me, a 200x is a "fun" bike. If I were to get another one I'd build it up similar to my old one. Good performance but not sacrificing reliability. It doesn't cost a ton to make them plenty powerful enough to have a blast on them and still keep up with most of your 4-stroke running buddies. Remember, you don't have to always outpower them. Sometimes it's better to simply out
ride them.
But that's just my experience and two cents. The important thing is to do what you want and have fun doing it. Get out there and race and find out what's what when you're done.
Oh yeah, I'll echo what's been said about stripping the gears. That really does happen. I've even seen it happen on stockers that were just ridden too hard.