Specialized has a prototype Demo 29er downhill frame in the pits at the Fort William World Cup. Miranda Miller will apparently be on the bike this weekend. The frame just showed up and there was not much practice time on them, so as far as we've heard (which isn't much), Finn and Loic will be on their normal 27.5 S-Works Demos.
The design of this alloy prototype is a departure from the existing Demo. It features what appears to be an adjustable/eccentric bottom-bracket, and not a concentric bottom bracket as you might initially think. The bottom-bracket doesn't appear to be attached to a linkage.
The bike also has an adjustable upper shock mount on the main triangle, along with some asymmetry in the chainstay area. It's possible that the upper shock mount is used to adjust the leverage curve and/or geometry. Dork out and speculate with your observations.
Prototype Specialized Demo 29 at Fort William