Totally agree with all of the above - if I'm playing modern country or modern rock, I'll definitely have a 5 string with me...if I'm playing classic rock or blues, probably not...
I've never understood this logic. I mean, I get that there's a certain "feel" to a 4 string neck compared to a 5 string, and that maybe it just "feels" better to play classic rock or blues on a 4 string. But if you are a 5 string player (as I have been for a long time now) and play a 5 string for other genres of music, why not just play your 5 string and not use the B string if yo don't need/want to. I do that all the time. If it isn't appropriate or tasty I don't use the B string. Just because it's there doesn't mean you have to use it. Just like having 24 frets. I play a 24 fret 5 string not because I always need it, but when I do, it's there. If I have a 4, I don't have that option.
I have tried to go back to a 4 string, with really nice basses - Sadowsky, Fender, etc. Yet, in the end, it seems like I always go back to my 5 string. Sudden transposition requests, low notes, position possibilities, etc. all keep me on a 5 string. That and the fact that my 5 string is a really nice bass with a great neck, tonal variation and great looks.
I still have an inner discussion (that sometimes spills out here) with myself about "simplifying" my playing and gear. Sell all the fancy stuff, get a passive, 20 fret, 4 string bass and deal with playing things up an octave, down an octave, whatever. After all, "insert name here" has done it that way, most bass players do it that way. Those of us on TB that have all the fance gear are like 1/10th of 1% of all bass players.
Here I go again...