Thanks for the help guys. The more I get to looking, I'm unsure now if I want the FS27, the P8 or the P9. Anyone have any insight or opinion on any of these frames for trail/mountain riding.  One things that bothers me about the FS27 is that one user stated it would be hard to fit anything over a 30t in the front.

Great thanks.  After so more considering, 17.5 looks like the way to go.

Having never owned a full sus bike, I am looking to build a CS-FS27 in 27.5+ but am not sure on what size to order.  I currently ride a Cannondale Trail 4 in a medium.  I'm 5'10 (178cm) with a 30" inseam. Any one have any suggestions on which frame would be a better fit?