If you tuned a 5 string to EADGC and didn't hate it, you'd probably have no issue with a 6 stringer.
I got a 6 string bass a couple years ago because the prog band I was in required it. Their basslines had all been written and recorded with a fender bass VI, which I refused to use (I'm a "bass"ist for god's sake not a "low-tuned-rhythm-guitar"ist) so a 6 string bass was the compromise. I didn't hate it, it was fun playing Primus songs on it as a party trick, but personally I found the high C more restricting than inspiring. Most of the time all it did for me was make the fretboard wider so I had to bend my wrist more to reach my low B. But I'm a 4 string tuned down to BEAD kind of guy
I got a 6 string bass a couple years ago because the prog band I was in required it. Their basslines had all been written and recorded with a fender bass VI, which I refused to use (I'm a "bass"ist for god's sake not a "low-tuned-rhythm-guitar"ist) so a 6 string bass was the compromise. I didn't hate it, it was fun playing Primus songs on it as a party trick, but personally I found the high C more restricting than inspiring. Most of the time all it did for me was make the fretboard wider so I had to bend my wrist more to reach my low B. But I'm a 4 string tuned down to BEAD kind of guy

