The X6 frames are pretty darn bombproof...we have had very, very few problems (if any) with those frames. Warranty says they rarely get an X6 frame back and when they do, it usually pretty obvious that the bike has had the ever-living crap beaten out of it. Our riders Eric Porter and Cam Zink each received 1 X6 frame last year and they are both still on those original frames...and you can only imagine what those guys put their bikes through.
How does it ride with a 71 degree head angle? Well, Cam Zink won Crankworx on his X6 last year, so I'd say that says it all.