I was looking into X9 hubs when I was searching for budget cartridge bearing hubs for a new wheel build. The measly 12 points of engagement was a deal breaker for me for trail riding, much less the technical stuff for the FS bike I needed wheels for. I ended up getting a Bicycle Wheel Warehouse (can't say enough good things BTW) set with their house branded "Pure XCR" hubs instead. I would strongly consider doing a Stan's build with their house hubs if I was building a wheelset today.
Let me know if engagement is ever an issue on them for you, I'm curious. I imagined ratcheting the cranks when crawling over a rock garden and stalling out due to not engaging again fast enough. Same, because they are otherwise the best value in sealed cartridge hubs on the market by far otherwise. I guess they had to shave that cost off somehow. You might not have as much issue with that if you are running 1X10 and never use a granny.
Not really a fan of Shimano brakes personally. The XT's I've tried feel way too grabby with not as much modulation as SRAM hydros. Almost like a really powerful mechanical brake. Could be just the ones I demo'ed and how they were set up, but I've demo'ed bikes with SRAM and they always had that same modulated feel. Other people swear by XT brakes though, so I could be wrong or just preference.
(Don't intend to sound like I'm bashing all your choices every time you post. I do enjoy seeing the photo evidence of your rampant upgraditis. Just my thought or experiences when I see certain components. I've played around with MTB components a bit, trying not to buy as much shit unless I literally need to replace something.)