I've actually considered the R as a potential backup to my 5D IV - frankly getting the same 5D iv sensor for almost $1k less in a body which uses the same battery is an attractive proposition on its own! I've almost dropped my 5D IV off of a few cliffs and I'm just waiting or the day where it actually goes over and I'm left with no camera on hand when I need it. I think in the end I will wait and see what the high resolution body looks like, and maybe the 5D IV becomes the backup to that. If it isn't what I'm after, then odds are I'll pick up an R and that will be the backup for the foreseeable future.
I know how you feel. I was going to get the 5D Mark IV and decided to get the R because it has the same sensor, costs far less, and for the additional ability to place the focus anywhere I want in my composition. I was skeptical of the ergonomics as compared to the 5D series (including the lack of a joystick), but all that skepticism is now gone.
Touch and drag took a tiny bit to get used to, but that's just because muscle memory had me sending my thumb out looking for the non-existent joystick when I wanted to change focus point, even though there is no display in the viewfinder of focus points like every DSLR I have ever owned. The R doesn't display them because pretty much the whole screen can be used to place focus. That alone takes away a lot of frustration when composing my photos. Then the focusing is so right on without any need of AFMA. Another frustration removed. The eye AF works great so far.
I thought the R body might feel too small to carry around my 70-200. As it turns out, I don't notice very much difference between the two. In fact, I think the grip on the R feels better in my hand than the 5D Mark III when carrying that heavy lens. It just feels right when carrying in one hand at my side, even without a battery grip... so I won't be getting a battery grip. People, sometimes, can be very resistant to change. I was never against mirrorless. I feared the ergonomics would be like those of Sony. I had high hopes that Canon wouldn't make one of those type of bodies and Canon came through with flying colors, in my opinion.
The EVF works great for me and is leagues ahead of the one on my little Olympus.
The only thing I miss is the second card slot. I miss the peace of mind. I don't need it around the house or around town. I feel I do need it for the model boot camps and fashion shows I volunteer at for a charity non-profit. I asked myself whether or not a second card slot alone would be worth the near $1,000 more a 5D Mark IV would cost. My answer to myself was that were I a paid event or wedding photographer, or if I was a paid photographer at all, it might well be. Otherwise, for me, no. I still would prefer the second card slot, but the trade off is the virtually unlimited focus points and no AFMA.
So for just $150 more than a 5D mark IV, I got the R and also the RF 24-105mm f/4L lens. That package is a great value if one doesn't mind f/4.
It will be interesting to see what the high megapixel model offers users. I'll hope to see what you have to say if you get one. It will probably be out of my price range enough to add a fast RF lens instead. 30 megapixels is enough for me.
I am seriously thinking of selling my 5D Mark III to help finance a second R. Having matching bodies would make things quicker to adjust to when switching between cameras when I want to carry two. I sold a lot of stuff to get the R.
I wouldn't hesitate to recommend the R to anyone who is looking to go full frame.