Thanks for the comparisons! I count this as 1620p. While there are occasional sawtooth artifacts in small areas of the image, they don't appear to be tied to motion. (It may be shadow dithering.) Therefore, I think this is a native presentation and not CBR. It strongly appears to downsample when running at 1080p.
Apart from the increased resolution, I don't see any notable graphical differences; AO, AF, textures, etc. seem identical in both Pro modes, so I assume it's not user-selectable but instead forced from the OS. We'd need comparative standard PS4 shots to examine if anything is improved on Pro over the base experience.
I've finally made updates to the OP. In addition to adding the titles in the change log, I also adjusted the summary so that it has a subtotal of officially enhanced games, separate from boosted ones. I did this because the Boost Mode list is becoming more and more stagnant; it shows fewer games than with official support now. In reality, there are bound to be hundreds more games which receive benefits from Boost Mode, far more than titles which are fully enhanced.
But once you get past the most popular hundred or so, it's very difficult and time-consuming to find comparative footage to look for improvements. I'll continue to try, but ultimately the list of officially enhanced games is more interesting to people, I think. They understand that Boost Mode provides nearly universal (if smaller) benefits, and this list is just a sliver that happen to have been examined. The official support list should be much more complete (but is surely also missing some entries).
As always, any assistance with images, links, or video is greatly appreciated! Please let me know if you have any comments or suggestions.