I've graded material using all of the screens from each manufacturer, including the 4000 nit monitor from Dolby that is the brightest of them all. I found that very little changed for me as a colourist - although it did require me to either grade on top of a transform (like the PQ curve) or under the same transform. I experimented first and found that both grading Linear Light under a PQ transform, and grading on a Log flavour like LogC/REDLogFilm/SLog3/CanonLog2/etc, also underneath a PQ transform, and all resulted in successful workflows. If I had to use any analogy I would say that it was like grading for a film deliverable again - I was grading under a LUT transform (although in this case it wasn't a LUT, it was a shader transform that didn't create clipping like a LUT can do).
I've been spoiled though and all of the material that I've worked on so far has been either C300 mkII, RED Dragon, Arri Alexa, or Sony F55. The thing I find that I have to remind some cinematographers occasionally is that your digital cameras have all been HDR for years now. What we're seeing currently is just the displays catching up to you. As such I found it quite enjoyable to grade using an HDR display as all of the camera RAW 'flavours' like .r3d/.ari/.rmf/etc all seemed to 'fit' on the HDR screens naturally (in terms of luminance and dynamic range). It was a very natural way to grade I found - although it does require the colourist to understand what their tools are doing so that they can select the right tool for the job. Some tools/systems only work in the data range between 0-1. If you're happy to work linear (which is what your cameras 'see' and what is usually what VFX prefer to work with) then some systems aren't able to work with Linear material that goes beyond 1 (hence why we still have all of the different Log flavours to deal with).
Most of my experience with HDR has been on a Mistika for grading, although I've done a small amount on a Resolve, and some more on a Baselight. In all of these cases I found that it was the colourist that was the limit of the creativity. If the cinematographer had shot and exposed the image well then the colourist should have no problems working with that image in HDR or LDR (low dynamic range). Its just important that the colourist and the grading toolset be able to work directly on the Linear Light material if that's the way you want to work.
It's also important to have access to Colour Management tools that aren't limited to 0-1 ranges like most LUTs are. Tools like Mistika's UniColour and Baselight's Truelight Colour Spaces work using mathematical shader transforms that are non-destructive (so that you can reverse them later) and are not limited to a range (for most camera transforms like LogC, CLog, SLog3, etc).
I haven't had the pleasure of grading to a Dolby projector but I have seen Star Wars at the Dolby cinema in London. That was using a 107 nit projector (as opposed to the normal 48 nit that we're all used to). As well as being brighter the main thing that I noticed was that the blacks were indeed blacker than usual for a projector (due to light bleed from the lamp in normal projectors). The blacker blacks and the brighter whites did indeed result in a dynamic range that was more than just a simple doubling.
It's the monitors that really change things in terms of displays in my opinion. Even just the 1000 nit ones create a huge difference. And I'm sure you can imagine how bright 4000 nits displaying a sunny exterior can be.