Wow - so much to say...I'll take the various themes one on one.
First - a little about me:
- Guitar player for 40 years; Blues, Rock, Metal, a few years of exclusively classical, solo/duo acoustic, and recently Keys & Bass
Next: Guitar players tune down PRIMARILY for singers, but when using extremely heavy strings (like 11+ gauge) may tune down for bending. I use 10's and can bend as far as I want.
Then: We call EADG(BE) E Standard or just Standard. I assume bass players do to. We call EbAbDbGb "Eb" or Eb Standard (Standard referring to the intervals), or just "Down 1/2 step). I again, assume bass players do also. Drop D is D ADG(BE) - Often used in both Jazz and Metal circles on guitar, and less often classical. I occasionally use Drop high D to play chords in standard tuning and slide in G. on the top 4/5 strings. I know - minds BLOWN!
For the Music Teachers out there: Go floss with my dirty G string. Not the one off my instrument. What a bunch of pedantic tight @$$es...I said D sharp because I was thinking about Drop D and just said this is like Drop D#. Jeez. [insert Steve Martin quote here]
For the Tune to anything crowd: Yeah, I get that, but certain things just work...Such as a Cello tuned in 5ths, or guitar/bass Drop D. Or the B string on a 5 string (vs any other note).
Just wondering if DROP Eb was a more common thing than me just finding it fast cheap and easy for a couple of tunes. I would by default just go all flat, or down toD. However - this just seemed to have a vibe about it to me. I don't know enough bass tunes to say if there are 387 tunes that you can easily play with Drop Eb or not.