I have 32 TALAS and a 32 Vanilla 140
32 and 36 are the stanchion diameters, 32 will suffice for XC duties (some manufacturers, including older SIDs went to 28mm stanchion, but they are a bit noodly, SIDs are now 32)
so, 32 either Vanilla (coil spring), Float (air spring, a little lighter) or TALAS (adjustable travel, air sprung) depending on the frame your matching with and your weight weenie requirements. I really like the 140 Vanillas but for adjustable travel forks, you'll struggle to beat TALAS (not saying you can't … Revs are good for example)
Are they worth MSRP? Well, I wouldn't pay 700 quid for a fork but then you don't need to as online discounting is very keen, I got my TALAS for half price and the vanilla came with the bike
Downsides; some folks complain of early stanchion wear, I haven't experienced this. Some other folks complain that FOX ask you to clean and oil the top seals every 15 hours of riding, but they never seem to mention that RS require seal lubrication *every ride* on their maintenance schedule so 6 and half a dozen to me.
I like 'em but if I could get the equivalent RS for cheaper I wouldn't fret the decision (I have 2 SID teams aswell …. SUPERB XC fork)