I do plan on attending a Worlds in the coming years, so it's important that the Piston rifle I practice is allowed!
I find it interesting that you don't see more of the TX200SR on the FT circuit. They can be a real pain to setup properly, and can also be temperamental, but when they're working, they sure work well. I suppose I've just answered my own question though: they aren't used by the top shooters because they aren't 'rock solid consistent'
I'm on the fence with what Piston rifle to use, I have a tuned versions of TX200 and HW97k also... I love shooting my SR though, but it may be smarter getting used to the HW97k (V-Glided) or the tuned TX200..