I kept one bass tuned in D standard until recently. I was considering a BEAD bass as well, but switching tunings is hard for me - I have almost perfect pitch, and when I hear "C" in my head, my fingers would want to go to where C is on a standard tuned 4 string - if I needed the low D, I had to practice with that bass the whole week before, to get my head in the right space so I didn't start playing in the wrong key. Ultimately, I decided maybe a 5 (for gigs where the music calls for it) would be a simpler answer, as at least C would be on the same fret from one instrument to another. Yes, what string to play was a bit confusing at first (why do I have a middle string?), but I'm getting more familiar with is as time goes on, and I think for me it's the right answer.