Have fitted a few sets of M8000 XT brakes now, every single bike has had an issue or other with the brakes! Not impressed at all, they seem a massive step backwards reliability wise compared to the M785’s…
I’ve got Guides on my own bikes, wouldn’t change them either. Been very reliable and worked flawlessly! The only thing I would say is the RS’ are worth the small premium over the R’s every single time, as the only difference is a cam in the lever but it gives them so much more modulation! The R’s feel a bit wooden by comparison, though again work fine and dead reliable in my experience.
If you must go Shimano, go SLX or some old M785 XT’s, but both are grabbier than the guides so not as nice in use.