Are there songs that you feel would suffer if the bassist used a 4 string instead of a 5?
Just curious what the community thinks.
I play a 6-string. I play a variety of music ranging from jazz standard to cover tunes. With the jazz standards I often avoid playing too much on the low B because, because I don't think it sounds right. Of course this can change if we are doing a modern interpretation of a song. For example, IMHO God Bless the Child sounds great with low notes if you play it in more of a modern gospel style. When I am playing in a jazz trio, I am usually expected to solo frequently, so the high C string comes in handy.
With cover tunes I generally try to imply the original artists intent rather than covering each song note for note, so basically I interpret the music a bit. I will freely throw in notes on the low B whenever I think it sounds right. I think it sounds right less frequently as the music gets older. So music from the 50s, 60s, and 70s I am not generally inclined to use the low B a lot, unless we are transposing the song down from the original key. When we do need to transpose, I think it's really nice to be able to play a classic iconic bass line in it's original form and inversion without having to jump up an octave.
Sometime in mid to late 70s, music started to feature notes that fall below the open E string. By the mid 80s it was very common to hear notes that fall below the low E string. Whether this music was originally played on synth or bass guitar I really don't care and I really don't put much thought into it. It's really nice to be able to play the low notes, especially in tune in which those notes are true to the original orchestration.
My Yamaha TRB6P has been my #1 since about 1995. I own 4- and 5-string basses, but I am most comfortable on the Yamaha. I tend to use it whether I need the B and C string, or not. I truly believe that it's better to have the extra range and color available that an extended range instrument affords. In all honesty, some aspects of playing become easier when you master a 6-string and some aspects of playing become slightly more difficult, so it's a trade off. But in my opinion, there are more advantages than disadvantages.
IMHO if you are content playing 4-string and it fulfills all of your musical needs, I suggest you just be happy with it and rock on. I started on 4-string and then transitioned to 5- and later 6-string bass guitar. The transitions were not easy and my playing suffered for a significant time. My opinion is you should start on whichever instrument you think you will eventually wind up playing. Best to avoid the transition if you can, because in many ways you basically have to unlearn how you think about the 4-string when you transition to a 5- or 6-string.