Kicking this thread off I wasn't sure about getting a fretless, I was just curious.
I took the plunge with a used sire v7 from bass direct which arrived yesterday.
I've only had an hour or so with it but I can definitely see the attraction! The resonance and tactile feedback is amazing. It definitely pushes you to different lines and more melodic playing.
Intonation isn't too bad, but i occasionally trip up, especially with stretches and holding on too long when shifting positions.
I need to do some work on the setup as the B string is choking out and will probably get some new strings.
So far so good. Thanks all for the good discussion and pointers.
Oh gratuitous pic (it came with the pickguard off for some reason)