I bought the A.I.R. 9 in August (size Small) and cobbled together as a SS: 32x20T drivetrain (EThirteen guidering/Surly cog), Fox Float CTD fork (100mm travel), Shimano XT brakes, Shimano XT crank set (revived for this purpose), XT hubs laced to WTB rims (TL), SRAM 9 speed chain, Easton EA70 stem, Niner carbon bars/seat post, Selle Italia saddle, ESI chunky grips, XTR pedals and finally GEAX Saguaro tires.
I'd not previously ridden a carbon bike (other than my road bike) so I was really psyched the first time I took it on the trail. Very stiff (climbing), responsive handling (cornering), and overall comfortable in the saddle. At 5'-7"ish, the fit on the size small was spot on (saddle a touch forward from center with a 90mm stem). The carbon bits (bar/seat post) made riding in the saddle a pleasure.