There are definitely some XC people who are more uptight than others. I find this out the hard way on our shop group rides. The really good xc guys (racers most) are pretty cool. It's the 'tweeners' (the ones who aren't fast or good bike handlers enough to be good racers but better than the purely recreational riders) who seem the most uptight. I get myself in more trouble, because I like to screw around (carry wheelies on climbs, play flattraker on the fireroads and stuff) and gawd forbid if I disrupt their cadence - - or pass them on a descent when I get tired of poking behind 'em - - by my antics. I find I much prefer riding with teenagers and early-20s riders. They still know how to have fun and not take themselves way too seriously.