I've had two vintage-style Sadowsky basses, an MV5 and a PJ5, both with humcancelling pups - no experience with the UV basses. Comparing the MV5 to my DJ5, I'd definitely say the MV5 was "rounder" sounding but I wouldn't describe the Sadowsky basses as having a vintage sound at all. The DJ5 with the Hanson singles, however, nails vintage IMHO. With that, I know that sound is such a subjective topic and we all hear things differently so YMMV.
I'm running an Audere 4-band pre in my DJ5 now. Set flat it sounds just like it did passive. Bump the bass up a hair and you get a nice, thick vintage tone. I've heard that, while a great pre, the East definitely colors your sound - the Audere does not. So, if vintage is what you're after with a little fatter low end, you might look into the Audere pre. It's definitely not the Sadowsky sound but, to me that sound is nowhere near "vintage".
Roscoe | Lakland | Music Man | Aguilar | Ampeg