I'm a demo'ing a 2012 Giant Anthem X 29er 0 that rolls just beautifully. It wears Giant's P-XC2 wheelsets. The bike I'll most likely purchase is the 2013 AX29er 2, which has the S-XC2 wheelset. The Giant website doesn't lend much info as to the differences between these two wheelsets (I'm guessing lighter rims on the P model), and I'm curious about how much of a difference in "roll-ability" these to sets truly exhibit with the same tires, etc.

Regarding hubs, I do see that they use the same front hubs, but the 0 I'm demo'ing has "Giant Tracker Performance" hubs on the rear and the 2 I'm looking to purchase has "Formula Sealed Bearings" on the rear. Can anybody shed some light on any appreciable differences between these two different rear hubs?

(FYI, for me personally, while I gladly acknowledge the usefullness of a lightweight setup, until I burn off that last pesky 10 pounds from my midsection, I'm not losing sleep over a few ounces on the rims. Basically, if I throw out the weight difference between the "P" and "S" models, will there be a noticeable difference between the two wheelsets for a guy who rides a lot but isn't a racer?)