XCR's vs MV, factory ammo experience
MV update. Previously most accurate ammo was Nosler VM 55g, didn't like hornady superperformance match 75 g. 75 grain is tightening up and is now reasonable, but surprisingly Winchester Varmint X 40g shot very well, almost as well as the Nosler. The SP does have a noticeably different recoil impulse and muzzle blast - I probably won't buy it again. Tried some Fiochi 55g FMJ as well, did shoot better than the American Eagle 55g I've got. If you can find some, I'd recommend it for practice ammo (I've only tried the two variety's of FMJ). 325 rounds downrange so far, no stoppages/failures/etc. No issues with any of my magazines including 2 ATRS 10 rd (please make more!), ASC 5 and 10 round, E-lander 5/30, Magpul 5/30. The magpul didn't drop free at first but does now. Very impressed with the Proof barrel and how quickly it cools down although I only shoot 5 shot aimed groups - no mag dumps etc. Did do a 1 10 round mag slow aimed fire - just for function testing

Before anyone says it, yes, I will do some formal accuracy testing when I get the chance and post some pics.
Very happy with it - will likely order a 6.5 Grendel upper for it soon. Currently my favourite rifle, bar none. Don't have extensive black rifle experience, but owned two different XCR-L's as well as an XCR-M in the past. Major difference is the trigger and fit/finish with the advantage to the MV. My $0.02 is I'd get an XCR if I was looking for a rifle for general use, occasional mag dumps, hunting and generally harder use. While my MV has been 100% reliable and I have a great deal of faith in it, the piston drive of the XCR and adjustable gas block is an advantage for reliability in touch conditions in my mind. Since I don't plan on packing my rifles with mud and seeing if they still work, this is a minor feature for me. The ergonomics on the XCR are also very good (IMO the biggest advantage of modern sporting rifles) and the easy availability of caliber conversion kits and uppers is a plus. I would say the recoil impulse of the MV is softer (none of my rifles wear brakes so that is not a factor), but turning down the gas on the XCR after break in helps (all of the three I've had were able to have the gas turned down very quickly without reliability issues during the break in period).
My recommendation - if you want an off the shelf NR semi-auto available in a variety of colours good for hunting, plinking and general use get an
XCR. If you want it your way - colour, hand guard, buttstock, barrel contour, +/- CFW barrel etc and accuracy is your highest priority I'd go with the
MV. I believe both are 100% reliable in any but the most extreme of conditions, but the difference between the triggers is too big for me to get past. For myself, I'd go with the Factory MV as well over the XCR. Again, just based on the trigger I am very confident its accuracy will be better than the XCR (which I found to be a 1.5-2MOA rifle with factory ammo and 2-3MOA with plinking ammo). YMMV.
I'm planning to get a Grendel for it and take it deer and coyote hunting this fall.