jd7, good question, right on target. I echo some of what koenkooi said about the EVF--except I do use it for little kids around home. (What else is there moving around here right now, besides wild life?)
Here's the biggest drawback of the EVF for me--but, in fact, it is not a problem with the EVF itself. I love to shoot early in the morning and late in the afternoon, as do so many photographers who relish slanted light, especially when it's golden light. BUT, the
EOS R's eye-cup has no easy way to be replaced with a Hoodman type eye-cup that works so great to shield the EVF from bright sunlight. My workaround is to wear a straw fedora hat, and that helps a lot, but I am hoping, hoping, hoping the 5R will have an eye-cup that can be swapped out for a larger one.
Now, that said, I became enraptured by the
EOS R and several of its primes and zooms just as I was getting back into professional portraiture. (Having two kids in four years, and then being the primary caregiver five days a week, and needing to make more money from a business that WAS doing great, I had put the photo biz on hold for several years. But late last year I created a small, pleasant studio for tightly controlled lighting, and I replaced most of my lenses and my 5DIV.) Then Covid-19 hit. In the two months of confinement, I've come to know the
EOS R and lenses even better, and I'm very eager to see a faster, more all-around mirrorless.
But being so focused on portraiture, last fall I consciously made the decision to sacrifice, for a time, some performance related to action and nature. In fact, I haven't had the time to get out with nature photography friends in ages, so, I even made the decision to sell my 100-400 and 5DIV so I could afford the RF 70-200. I kind of regret that decision at this point, but, from a business standpoint, it made sense. With all this at-home time, I imagine many of us are second guessing, but it's done, so, fine.
Just yesterday I dusted of my refurbished ef 70-200mm f/4 IS which had been so fun for travel. I still have an 80D. My goodness, was it fun to get out and use for quick, sharp shots, and, I will admit, the OVF just seemed so much more suited to fast action.
So when I said that the R is "the best," I was still thinking in terms of portraiture, landscape, real estate, macro, and product type photography. For action? No way. I should have qualified my assertion, absolutely!
Future purchases are going to be much more strategic. It might be a long time before I can take trips with friends "just" to photograph some birds, and I never did have much interest in sports photography. If in five years or so the kids are into sports, maybe...
But for now, for my purposes, a mirrorless that allows such precise, consistent exposure and AF, with an EVF that is so close to true WYSIWYG, even with DoF preview, and with all the positives koenkooi mentions is what I need. Plus, even though we are speaking a matter of degrees, several of the Rf lenses are better than anything I've ever used--and they work so well on the R.
Maybe the 5R will bring more
dSLR performance? We can only hope!