Personally, I think of the BS Music Library as kind of a useless novelty with SPC music around. It's like a nifty SNES-driven frontend, if you want ... a japanese one though. Nothing that a nice CT Winamp skin can't best.
The Jet Bike racing in Chorno Trigger isn't that great either. More like a try of Square to put some Mode 7 effect in the game because every RGP on the SNES used it at that time (worldmap anyone). Can't miss out on that, of course. Is the BS Jet Bike any different from the game's? New drivers, gameplay revised, more tracks/backgrounds? I never checked it out myself.
Now the Character gallery, that's something. Does the PSX version have it too and if so, was it translated. Anyway this is a great little ROM to see how much effort and detail Square poured into this game. 2D RPG at its prime.