I did not remove my board when I upgraded to the Dark Rock Pro 4. It also comes with a screwdriver that is long enough to install it. The height includes the bracket. I believe It's measured from the top of the CPU.
Just a heads up, if you do go to the DRP4, the corsair rgb Pro ram will be too tall to use the front fan,though It'll work fine without the front fan. I also upgraded my cpu cooler after my system was built and it wasn't that hard. good luck
Due to my ram height, I'm running my DRP4 the same way. Kyle at Bitwit did a review of the DRP4 where he tried to run it passively. He found no temp difference between 1 or 2 fans.
I just replaced my Wraith Prism with the Dark rock pro 4. If you take off the first plastic retaining clip and replace it with the DRP4 clip, then do the other one, should should be all set. That'll keep the back plate in place.
I just installed this cooler with the Corsair RGB Pro's. The cooler covers the first RAM slot. This shouldn't be an issue if you're only using 2 sticks with this board, but you won't be able to mount the cooler's front fan.