This is mostly to get the opinion of various people, since they're different games... somewhat:
B&W:
+ Text skipping with SSAB (though this might work in DX too, haven't checked)
+ Text skipping with B
+ L2 boss throws flames faster
+ Faster start menu popup/popdown [1]
+ Ability to use select-warp [2]
+ Lots of other small gitches
+ Warp sequences are probably shorter
DX:
+ COLOR! weeeee
+ Color dungeon [3]
+ Warp sequences are probably longer, due to the game's horrible, horrible lag when manipulating a color screen that way
[1] Start menu popup times:
B/W: 28fr
DX: 52fr
(time was measured from first frame of pushing start to first frame "[ ]" cursor was onscreen)
[2] This would be used twice in the run (or, at least a test run), mostly just to keep Marin through the whole game as a purely asthetic effect. The only problem would be a minor route adjustment (getting the orcarina, talking to her right after) and probably cost more time (from her "I'll wait outside..." message) but would at least add in some variety
[3] Even though it would prove useless, unless it's a 100% run (and even then, blue would be useless and red knocks enemies
away...)
So, personally, I'm torn. B/W has better speed potential, but DX has ... uh, color.