Technique-wise I know the electric won't apply much to the upright--but the theory will, and probably the rhythm as well.
I've seen some 3/4 uprights around here but I'm 6'2" and 220 lbs. I make those things look like cellos. Anyway, this is something for future planning, once I start developing my bass chops.
Right now I'm focusing on 4-strings. Frankly I'm not really sure what one does with the 5- or 6-string basses unless one is a god-like player.
Here's what I picked up yesterday. It's a Schecter....something. Custom 4? I got it for under $200 (gently used) and I see they street price at 5 and change. The satin finish and flamed maple top on the mahogany body is what caught my eye. The smaller-than-typical body and headstock are nice, too. I know that Fenders are the gold standard but I dislike the goofy proportions.
A Gretsch also caught my eye but I'm not ready to spend 9 bills on an instrument I may not take to.
G5442BDC Electromatic® Hollow Body Short Scale Bass by Gretsch® Basses