I've had mine for a while, and love it. I'm a bit over 6" around, and the wonderwave has been great for me, although you have to stretch it out a bit at first--the easiest way to do it is just to invert it once or twice. It can be difficult, but it helps a lot.
Also, I recommend against the colorless inserts. The maintenance on them is a huge pain, but the colored ones are not too bad in my experience.