Yea I think I tried to say that in my post. We were listening to a Johnny Hartman record from the 50's in my van on the way home from tonights gig and I was thinking there's no way I could do that justice with spirocores. The breath of guts leaves space that you can't get from steel. Steel notes are way to long and the envelope is wrong. The proper tone for that gig is a poof with a tuned note that is vapor almost as fast as it appears. The space in between leaves room for the beautiful music that steel would otherwise clog up. I wish people wanted me to do those gigs. I can't get em.
That is a great way of describing it. Love Johnny Hartman, BTW.
That sound is really what got me going on the bass at first... developing the sound in my head when I was just a little kid, listening to vinyl at home. Not just jazz classics, but most of the pop records of that time featured gut strung basses.... the Sinatra stuff, Nat Cole was huge for me...everything, really. I was still a few years from even playing a bass, but that sound stuck in my head. I was just a toddler, so it just got ingrained in me that this was how the bass sounds. Now I can reproduce it if I want to.
Thing is; with these Gamuts on this bass (in combination with the Evahs on the bottom), I can also get a more modern, singing thing going as well. So it appears that a lot of my fears of the bass turning into a one trick pony were largely unfounded. They're a lot more versatile on my bass than I expected.
Sorry for all the blather... it's a bit of a time of (re)discovery for me.

I wouldn't know much about gut strings on my bass if a couple of guys hadn't been really generous recently.