There's only two things Drop D tuning on bass will accomplish IMHO: Gives you the low D on a 4 stringer..... and if the original bassline was written in Drop D and the bass guy was using standard fingerings it'll be easier to play if you also are in drop D. You *can* play any bass line in any tuning (assuming the notes you need are there, like the low D), you just might have some weird/tiring fingerings.
As a beginner, learning in drop D may confuse the crap out of you (second fret is now an E....instead of a Gb...). A Hipshot D tuner would eliminate that.
My group is tuned down a half step.....but to eliminate mental confusion when we call out notes and chords we call them as if we were tuned up. That way an A is still referred to as an A and there's no "ok, you mean Ab like it sounds or you mean A like the original?!" which trust me will screw with your head.
I started playing on my 4 and we did a couple songs that were in drop D, until I got my 5 I just played the D somewhere else instead of open. My 5 eliminated the need for retunings (something I still can't do by ear


) and eliminated the mental gymnastics

Long story short, as long as you are playing the required note in the bass line and it works you don't have to retune... if you really need that lower D, get a hipshot or a 5er

. (my opinion)


Guitar is a whole different story in drop D, changes the chord shapes.