I (pretty much) play 5ers exclusively and am happy with my Stambaughs.
However, knowing what I know now, if I had to do over I'd probably go with a 4 string tuned DGCF, plus a hipshot tuned to C.
The downsides would be losing that open E which comes in handy for a lot of tunes and styles, and having to relearn the fretboard.
Yes, I could just transpose everything but I know the sound of my notes (especially open strings) too well for it not to freak me out if I played an "E" but the actual note I heard was a D. I'm just weird that way, plus it's way too late now lol.
For any "custom" tuning I would have to spend a lot of time unlearning decades of muscle memory. Not worth it to me at this point in my life/career.
What I DID do was tune one of my basses (low to high) CGDA, similar to New Standard Tuning, as used by Robert Fripp (of King Crimson fame).
It allowed me to have a similar feel to a 4 string, but with an extended range that the dropped two steps on the lower and up one step on the upper string provided. Since this tuning is in 5ths, it made it easier for me to play typical "guitar" power chords or add in those "extra notes" that you generally have to "reach for" on a standard (or BEAD) tuned 4 string. It was also quite a nice treat to use this tuning for independent left/right hand bass/chordal melody interplay (ala Chapman Stick or Warr Guitar styles).
It worked for me. Didn't miss that low B (C worked out quite well).
I may revisit this adventure at some point in the future.
Cello tuning. This is the only one that really seems worth relearning to me. I don't really use the low B but I like to use C and D. I always screw up when I play cello so maybe this would help both bass and cello playing. Maybe someday when I have more time to retrain myself...like retirement.