Hi Rick...as I recall, the M5 is 24 MP vs the 32.5 on the M6 II. Which, really, both are goofy levels of high pixel density. Quickly playing with it, the M5 is ~62 MP FF equivalent and the M6 II is 82.5 MP FF equivalent. Honestly, over the 5DRs, I wouldn't see much of a reason to us it either. It does have a higher FPS, but I think the reality of most modern cameras is that they are all very capable.
I have been/will be looking more at M6 II on the 500 vs the 5DIV plus 1.4 TC on the 500. AF speed/precision but also IQ and bokeh considering I can run one at f/4 and the other at f/5.6. I will also see about adding the TCs onto the M6 II, but I have already been playing with that and I currently think that is an AF hit.
While I am simply playing with the cameras I have at home with me, part of this is planning which camera will be mounted on what if I decide to shoot with two bodies in Yellowstone.
As for the M series, yeah, the main niche other than being a novelty I found with the M3 was for video. I forgot to mention, but that was another reason I upgraded, I figured the worst case scenario was the M6 II would be a better video camera with better AF, AF tracking (much better over M3), and AF at lower EV (-5 EV on the M6 II vs +2 on the M3, which had been an issue). BTW, M6 II is a great video camera, for my needs.
Thanks, I edited the initial post to include the resolution. Looks like I typically cropped out half to two-thirds of the pixels.