I've tuned 4s to BEAD and used 5-strings. I've settled on the 5 because I like having the regular 4 strings in addition to the low B. I don't use the G often, but when I do I'm glad it's there.
Yeah I have tried the BEAD fours but never sticks. I think I would be more comfortable having the EADG still at hand and the extra low B above. Is it a devil to match up qith guitarists tuned down though? Since you are playing on different frets. Ah why I am worried about that, been a couple years since I jammed with anyone anyway lol