After reading about several XX1 builds on the forums, I decided to give it a try. BUT, rather than spend the extra cost on the 11sp cassette, 11sp shifter 11sp hub and 11sp chain, I just got the XX1 crank/ring. It works perfectly with my current 10sp shifter, 10sp chain and 10sp Type2 rear derailleur. I took it on my local trails over the weekend with no chainguide and I could not drop the chain once hitting various jumps and drops. So if you’re thinking about making the XX1 switch, consider using your existing 10sp setup and just get the XX1 cranks. No need to file your carbon frame drops outs to deal with fitment issues. The cost for a "complete XX1 upgrade" to add only one additional gear, plus having to modify your frame was not worth it to me.
By the way, I opted for the 168 Q-Factor. It fit perfectly with no clearance issues. I had to switch the bb spacers around to get the cranks to snug up tightly (no spacer on the driveside, one spacer on the non-driveside). Let me know if you have any questions.
If you're not going 11 speed why bother with the crank? X9 or XO cranks and a bling ring work well. Is it just to avoid a guide? For me the difference between a 36 and 42 tooth cassette is massive. It's not like having one extra it's like having 2 or 3 extra gears its a get out of jail free card on steep climbs. Also the 156Q factor work fine on my large and no filing necessary on the dropouts.
I wanted a lighter crank and no-guide setup. Don't get me wrong, I love the "idea" of the xx1 additional bail-out gear. But not for the added cost of $1000+ plus the possibility of having to file your frame dropouts (depending on you hub brand). Although you didn't need to file, even Ibis suggested to file your drops outs if you have fitment issues. I picked up my xx1 cranks for only $240 after the 15% off discount code at Universal Cycles.. The XO cranks are $430 plus $60 for the BlingRing. $490 vs. $240 = no brainer for me. Also, I'm pretty sure you still need an upper guide with the BlingRing since the teeth are not tall like the xx1 chainring. So for only $240 bucks I dropped a bit of weight from my old XT crank and chainguide combo and my bike runs pretty much dead silent now.