I had a 5 string I strung with real light gauge strings and tuned to drop C with a extra high string but I didn't use it and didn't care for it much
I've done that too, with the same results.
I prefer to keep my 5 around for variety and for jamming on standard tuning stuff. Being active it also has a slightly more modern sound. But, in all my serious band projects I play vintage'esq 4 strings.