The covers on the black bass are original Gibson pieces the owner supplied, there's a guy in Texas that makes nice repros too. I picked up a couple of his off of Ebay for a great price - thinking that since the bass isn't an original Gibson but uses parts patterned after one including Scott's bridge, they'd make more sense.
I happen to really like the chrome covers, (CHROME = SEXY) aside from their contribution to a 'Bird's overall aesthetic they don't cramp my (admittedly bad!) pick playing style at all - and usually the outside edge of my pinkie finger ends up resting or contacting the bridge cover.......and that doesn't make for such a large callous there like the saddles and strings of an uncovered 3 point can do.