In Germany's forum a few seem to be playing them.
They do glaze a bit, rest seems quite OK, people seem to think that the hardness is not really well described, so you'll need to check that.
Rainbow seems to have more problems due to the coloring.
I do feel they are way overpriced and yes, the distributors seem to do price fixing.
The completely blue ones are marketed as a Snooker tip, if I'm not mistaken?
Cheers,
M