I've had a Blackbird for a few months. Quite a capable bike:
Stretchie has his still. He does a fair bit 2 up, more than I did with it. Comfortwise its fine. Maintenancewise a few things can be a faf but overall nothing to bad. If you're looking at originals check that the linked brakes still work, other than that expect the suspension to be a bit tired and in need of a fresh and then the usual things relating to condition. Oh they also have a cam chain adjuster issue which I think is fixed by replacing with a later models part. Stretchie can give you more details if required.