The strength issue is worth considering if it's a bike you intend to use regularly and properly.
I suspect a sub 25lb FS XC is going to cost a considerable sum ( my rigid XC is more than that
) and then for me there would be an element of protecting it and not fully enjoying it.
Just think of it as weight training
I could probably get my full sus sub 25lb - but what I don't want to sacrifice is reliabiilty.
My Weight-Weenie consultant has already offered me carbon bars - maybe I should see it as a challenge - but I don't want to be stranded haflway round the red route at Brechfa cos some lightweight part has given way.
@ Twain - yes chains and cassettes can offer a significant saving. I'm running a KMC SL9 and an XTR cassette on my lightweight.
Wanted: Trek XO2 54cm
Running:- Orange AluO; Orange Gringo; Orange Evo2; Trek Madone 6.9 SSL; Trek 1500 SLR
In Progress:- Orange Elite; Trek Elite 9.8
Selling:- Orange Sub3; Orange O2
Sold :- Merlin Titanium; Specialized 99 FSR Elite; Orange Mr XC; MountainGoat WhiskeyTownRacer; Orange AluO