Interesting, thanks for sharing your experience. I'm too quite pleased with the 5DsR overall (although its DR is over 1EV less than 5D4 as far as I could see), I just can't expect the level of shadow cleanness that comes out of modern Nikon and Sony cameras.My biggest problem? I'm in need of a new body sooner rather than later. I don't know that I can wait for Canon to slowly come out with new tech. I've got a 5D Mark 3, and a 1DX (Mark 1). I've had my main board and my sensor replaced on the 5D3, and then recently had it modified by Spencer's. I've rented a 5DsR a couple of times and was pleased once I corrected technique issues, but I've been hoping/holding out for an updated version. I don't know that I'll be able to wait long enough and that bums me out. I wasn't impressed with the 5Dmk4 over my mk3 when I rented it, but I loved the huge leap in megapixels the 5DsR had over my 5D3. I wasn't seeing huge DR gains with what I shot on the 5Mk4 vs the 5DsR, so while it may be there, the type of shots I take don't necessarily show it.
Also, the greatest asset from all my photo gear are my EF lenses. That pretty much locks me down to either Canon or Sony. Canon has great lenses and the closest contender to me would be Fujifilm. Switching to Fujifilm however (GFX-cameras if anything), would mean buying a completely new, expensive, system with few native lenses, and not really being able to reuse any of my current lenses. Even if I could try to adapt some, I don't expect the output to be really good - both due to vignetting, since my lenses are designed for 35mm sensors (not MF crop), as well as other optical performance degradation due to incompatibility.
So I resort to patience - mainly thank to not having an urgent need of upgrading.
If you need to upgrade, there shall be used 5DsR bodies for second hand prices - probably worth taking a look if you liked its output.