I pilled the trigger on the cs-821 17.5 frame from peter in the end. All I can say is WOW, What a bike. I think its been mentioned before but the hardware on this is another level compared to my old china full sus. This has a shorter chain stay and slacker head angle than my last frame and its made such a big difference, I find myself hammering on the downhills now and really flicking it around corners. The power transfer to the rear is 10 times better on the ups, even with shock fully open!!
As far as the build went, it couldn't have been smoother, I picked the frame up at 6pm friday night and took it for its first spin around 10am the next morning. The bearings/bolts were all nice and tight and the cable routing was a piece of cake with draw throughs in place.
If anyone has any questions about this frame just hit me up, I'd be happy to help.