I'm a 6-string guy myself. I started on a 4, moved to a 5 when the treble to bass clef transpositions my teacher had me do went beyond the range of my 4 (and I was hopping all over the fingerboard), and recently went for a 6 when I found myself playing a lot of melody parts/stuff (like Disney) in my kindergarten classroom (since kids' hearing isn't as attuned to lower frequencies; why else is much children's music so high pitched?)
Most of the magic in my playing happens on the EADG, but for when I want to go off on tangents, I have room. Cats like Victor Wooten humble most all of us with the amazing things he can do with a 4-string. Tony Levin and the late Mark Sandman have shown us that amazing things can be done with 3 or 2 strings respectively. But for many of us, the extended range is what works best for the music we play.
If you think a 5 or 6 will enhance your playing and allow you to find 'your' voice, go for it. It's not cool for bandmates to tell you what gear you should or should not play. The only way you can play well, play confidently, and add your personality to the band & its sound is if you play your bass that you're comfortable with. You're the one playing the bass, not them.
I've been lucky. So far, I've never had objections from bandmates/potential bandmates for playing a 6.