I currently play in a band in which guitarists tune in drop B, I tried to tune like them, but I discovered I couldn't find any string gauge which work (for me of course) in that tuning, so in the past years I simply keep the bass in standard tuning (BEADGC) and just change the way I play songs, in the beginning all of the 9th were a problem because it's a position for the left hand which I (almost) never used before, but now, after a few years it feels like a 5th to me, I think (expecially in a metal enviroment) what you should care the most is to have the lowest string tuned like the guitars (or lower), the rest is just left hand positions