I was able to pick up a new CableCard from my local Verizon FIOS store. The folks in the store didn't really know anything about the different Motorola part numbers, but after inspecting the card to assure it was correct, I went on my way.
I installed the card and attempted to provision the card using the Verizon web site. This worked for some content, but not the HBO/Cinemax channel block. I then called the Fiber Help Desk and went through the usual Q&A with the tech. Eventually, the tech mentioned that Verizon has a tech note describing the "incompatibility" between the Roamio and the various CableCards. After going off to research that for a few minutes, he called me back. He didn't actually know the part number printed on the card, but described them as MCPOD1, MCPOD2 or MCPOD3. I convinced him that the part number on the card was correct and he escalated the issue to a higher level tech. That tech gave him additional instructions as to how to re-validate the card and magically, it began working.
For now, all is good!
TiVo Roamio Plus 1TB (lifetime service)
TiVo HD (lifetime service)