The Sweet Spot

Here are some that show what I'm getting at:

This shot with the R and 85 F1.8 wide open wouldn't have been as good. The depth of field would have been shallower, and the optical quality would have been worse. This is the very shallowest depth of field that I would accept for this shot. In fact, if I were to do it again, I'd probably open it up to F2. To get similar depth of field with the R and 85 F18, I would have shot it at F2.5 or F2.8. The result would have been similar to this, but the Sigma is a better lens, so this would still be a better result. Of course, for thousands more (and lots more weight), I could have used the RF 85 F1.2 lens at F2.5 or F2.8.

One more with the 56:

Again, the very minimum DOF that's acceptable to me. It would probably have been a bit better stopped down to F1.8 or F2.

Now some with the 32, an amazingly good and versatile lens:

Again, this is the shallowest depth of field I would accept for this. The R with 50mm lens would require F3.2. The adapted 50 F1.8 would work, but wouldn't match the optical quality of the EF-M 32. You could adapt a bigger, heavier and more expensive Sigma 50 Art, or use the even more expensive RF 50 F1.2. You could shoot those lenses at F1.4 or F1.2, but the result would be much worse (because of the shallower depth of field). Shot at F3.2, those lenses on the R would give you a very similar result to this.

I like this, but again, should probably have stopped down just a little. No combination of full frame camera and lens would have improved this.

Again, shallower depth of field would not have improved this shot. Nothing about a bigger, heavier, full frame combination would have been an advantage.

And the Sigma 16 F1.4. I'm so glad I got this lens, despite my initial misgivings about whether it would give me opportunities I didn't already have with the 22 F2 and 11-22. It obviously does.

Better with shallower DOF? Obviously not.

And the next three are the kind of results that make me love the Sigma 16 on the M6II:

Can you do these on the R with 28-70 F2 or 24-70 F2.8? Yes. Better results? No. Bigger, heavier, (much) more expensive? Definitely.

Once you lose the fixation with the shallowest possible depth of field, and consider what actually makes for good portraits of various kinds, you realize that the M6II, with available lenses (EF-M mount), can do pretty much all that the R can do. Are there some situations where the R and full frame lenses can get you better results, even if only marginally? Yes, of course (though your examples weren't of those situations). Is the slight improvement for those few possible situations worth the extra expense and weight and size of the full frame combination? That's a question for each of us, in consultation with our financial advisors and personal trainers. Is it worth a difference in score on a review? That depends on whether the scoring is relative to other cameras in the same class, or to all cameras available. If the former, no. There are no other APS-C cameras that do better than the M6II. The latest Sony and Fuji APS-C will do as well, especially with the same lenses (for Sony) or similar (for Fuji), but not any better. And no, the difference between 1.5 and 1.6 crop is not relevant here. It's utterly trivial. If we're scoring relative to all cameras, perhaps the R is worth 5/5 and the M6II is worth 4.5/5. But even that difference is too large, for the tiny number of possible situations where you'll actually appreciate the difference in results.