I've just got a Raptor 10 in time for the summer. Am going to keep my old CB and use the Raptor bladder in it for rides where I need to carry a little more.
So far, my thoughts;
The positive;
Bladder is excellent. Easy to fill, easy to open and easy to put in to a full pack.
Overall pack design is very clever. Love the little mesh pockets on the hip belt and the helmet holding thingy!
The magnet for the bit valve is genius.
Good, well organised pockets, especially with two pump pockets (Shock pump and tyre pump) as well as seperate pockets for keys etc.
Sits really well on the bag (I have a M/L sized one)
Ventilation seems very good, but not really tried in hot weather as yet.
The negative;
It's a little heavy.
The bladder hose can only run on the right hand side of the bag (I usually like to run mine on the left)
RE the stock/availability, I got mine in Cycle Surgery in that London's Famous London. If you're not around that way, best try and outdoor shop, as I've only ever seen Osprey as an outdoor/climbing brand and I think they're pretty popular there.