mea culpa
Yesterday, I had the chance to listen to the bike as a spectator, rather than a rider. I have to say that it is, in fact, considerably quieter with the Q. It also has a deeper, throatier, less raspy (less annoying?) sound. The bike does seem to have lost a little bottom end, as someone mentioned in the mini forum.
The rear tire slightly rubs the silencer on near full suspension compression, even after spacing the silencer out what I consider to be a reasonable amount.
If I had it to do again, I think I would modify the stock end cap to divert the exhaust sound towards the ground instead of buying the Q, mainly because of the fitment problems.