I am also in the market for a docsis 3.1 modem. What are you going for?
One thing I like about the SB8200 is that if I ever go back to running a "business" connection at home I can have a second IP assigned to the second WAN port it has.
I also plan on modifying the modem to fit into my network rack without a shelf like so: https://www.reddit.com/r/homelab/comments/ft579e/finally_got...
So the actual internal matter a little bit to me as well.
It's in my "never touch again for any reason" bucket now as a result.