So the "compression stop on pex" confusion/question I had was answered when I took these off. They are compression but had a long metal insert so they were something that was made to handle pex (or perhaps CPVC). They are not just the standard compression stops I see everywhere for use with copper (or rather they essentially are but came with the insert).
View attachment 90896
For the heck of it, I got some brass/chrome-plated sleeves like wwhitney
mentioned, though these brasscraft ones are 3 1/2" and I could have used the extra 1/2 from the 4" uphonor. Had to chop down the pex a little to get the compression ring off but there is still plenty exposed. Everything installed without issue but after turning it on, the cold water hose was leaking from both ends even though I never even removed it from one side. But it is my fault as I should have planned on replacing the hoses when I did the valves anyway. Quick stop to ACE and it is all hooked up and leak free.
I didn't cut them to the same height as I didn't want the dishwasher line blocking the cold shut-off. There is a lean on the hot side caused by pressure from the hoses (as I had to do a straight instead of right angle stop at the top) but it doesn't affect anything so I'm not worried about it.
View attachment 90895