Small progress update:
About finished with the Driftveil/Route 6 area (complete with some truly excellent custom music from regen), working on Chargestone Cave now.
Also, on the advice of highly talented hacker Rangi, I've implemented diagonal-movement sideways stairs, and have begun redesigning older maps to make use of them. So the maps will be a bit more dynamic and less flat looking in the next demo release (or final release, if I don't end up putting out a 4th demo).
Also been debating on the eventual title for this project. Not fully decided yet, but I've been debating the name "Pokemon Black and White Genesis".