2.1's? Do they still make those?
Of the three listed, I've only ever tried the High Roller (and in 2.5 ST, no less), so I can't comment on their effectiveness as an XC tire. I know mtnbiker66 loves 'em, but he also rides in some pretty rocky conditions.
I know you didn't mention them, but for the terrain you describe, I am a fan of the Ignitors in 2.35 60a, especially in the front. They rolll pretty fast and hook up in the corners really well, considering. I'm currently running the Ignitor front and Larsen TT 60a in the rear (although I think I may try a High Roller semislick in the rear after the TT wears out).
Hope this helps - just a reminder that my advice is usually worth exactly what you paid for it.
