RE XTR: interesting you note that the lower specs "should be almost as good". Late last year I replaced the OEM NX group* on my Slash and installed an SLX shifter and mech with an XT 11sp cassette, and I don't think this shifter is capable of much. There's a remarkable amount of slop in it fresh out of the box, especially for upshifts. I highly suspect it's engineered in to justify the jump to XT (because really, what else really separates these groups? Serious question.) I'm due for a dropper post service and I may as well install new shift cable and housing while I am at it because this SLX unit is a turd so far. I'll chime back in after the service is done.
Also, another +1 on this format.
*While not flashy or remotely lightweight, the oddball 11sp/HG driver based NX group from '18 wasn't bad. Honest to goodness ka-chunk shifts, mech never failed, and it lasted two full seasons in the NW. Ultimately it was the mech that just plain wore out. I've wanted a Shimano bike from the start so I swapped when the time came. Guides were swapped out for SLX stoppers last year too.