Ok, I have to rant a bit. It seems that an issue I had been having intermittently with my rMBP sometimes disconnecting USB ports was not Sierra or the Mac hardware. My i1 Display Pro has developed a break or short in the USB cable up near the device. The problem started just after the 2 year warranty was up. I know that Xrite products garner favor here over their Datacolor counterparts, but My old Spyder 3 lasted longer than that. And, I expect more from Xrite.
As a recovering engineer, I have never liked the physical design of the Display Pro. The "footprint" is too narrow, making it less rotationally stable when trying to make it lie flat on the monitor. Far more egregious is the flimsy, spaghetti-sized, soldered-in USB cable. And they put a *counterweight* on it! Really? Given my 2-week calibration period and sometimes going way over that, I would say this DP has been used about 50 times. And, because of my rightful distrust of the durability of the cable, I have really *babied* this thing from the get-go. I am less than happy.
I have an i1Pro1 Spectro (2 actually) that I can use. But, as you might expect, I get higher black points with it. For profiles that i want maximum contrast ratio, My PA241/SpectraviewII goes from over 600:1 down to 412:1 with i1 Pro.
I have an RMA request in to X-rite to see what my out-of-warranty options are and their costs. I will not buy another i1DP at retail. I can get the low or mid-range Spyder 5 for much less, and I wouldn't use their software anyway. (The Spyder 5 hardware is not crippled at the low end like the Colormunki Display is.) If necessary, I can calibrate it with the i1 Pro.