The deal is this:
Plugboards work.
The Sony will detect mismatches between the DB and ePub.
When a mismatch occurs, the Sony updates the DB with the ePub's metadata.
This puts interesting limitations on plugboards and "use author sort" that worked fine with previous models:
1) It won't work with DRM'd books, as the metadata in the ePub will always win.
2) The T1 will actually spend more time reloading data when it detects one of these mismatches, for no real benefit.
Kinda disappointing, really.
EDIT: I think I've pretty much reached the end of what I can do with this driver at this point. It's about as close on feature parity with the 505 driver as it is going to get with the current Sony firmware from my perspective. Should serve as a good starting point for users.