I'm a hold out for sure. I still ride a 26er, and until this week was on a 3x9. If it aint broke don't fix it has been my motto. Given a really good deal on the X01 group, I modified my XTR cranks with a narrow wide chainring and went for it. I dropped over a pound, cleaned up the cockpit, and simplified my shifting. There has been zero chainslap since, zero missed shifts, zero "oh s@#$ I can't get the gear I want moments". I'm loving it. That said, I cut out my two top end gears and three bottom end gears by making the change. I've spun out a couple of times, but really, who needs to go faster than 34mph on a mountain bike. I've also done a couple longer climbs of 3000' where a gear or two lower would have been OK. That said - I'm sold. I've been a life long shimano lover, but sram's got a winner with these groups.