I switched from fretted 4 to fretless 5 and have no intentions to go back.
For me the more massive neck feels better (and I also believe more massive necks yield a more massive sound but that might be debatable) and having the low B as the occasional option and as a thumbrest is great.
I am not using the low string as often as the other four but if I play on the E I don't have to rely on the pickup or whatever as a thumbrest.
I can't comment on how big the change from 4 to 5 would have been since incorporating the step from fretted to fretless was probably the bigger one and distracted from the additional string.
For me the more massive neck feels better (and I also believe more massive necks yield a more massive sound but that might be debatable) and having the low B as the occasional option and as a thumbrest is great.
I am not using the low string as often as the other four but if I play on the E I don't have to rely on the pickup or whatever as a thumbrest.
I can't comment on how big the change from 4 to 5 would have been since incorporating the step from fretted to fretless was probably the bigger one and distracted from the additional string.