Got my order in as well just now.
My only concern is that the active backplate looks to be thicker than the passive OEM one I have now. The OEM one just barely clears the RAM sockets on my Asus Rog X770 Crosshair VIII Formula. That said, from the pictures I see, the acrylic on the back does fortunately not extend all the way down to the PCIe connector, so hopefully it will clear.
I started out with the 3998 Hybrid KP, then I got the 1999 HC Kit and now the Optimus. This sure is adding up to one expensive GPU!