I'm 6'0" and for awhile was at 190lbs and TE2 fit me fine. In fact, I had to *trim* the ab & kidney to make it work. The largest person to make TE work was CMANavy (not active much) was 6'4" 235lbs IIRC and shimmed TE enough to fit him and it looked good too. I've also seen FX on someone very small (e.g. 5'4" and barely over 110lbs).
IMHO there are guidelines that we put out, but in the end any armor can pretty much be made to fit anyone. Unless you are lucky enough to fit something out of the box with no shim/trim (like I was with the old FX), you're going to work the kit regardless.
I'll agree that RT is a good "big boy" armor though, but it's not like it's the only option.