I have a user 35/1.7 i've been thinking of parting with. It's optically pristine, bought it off here a few years ago, one of my favorite lenses ever. Downside is that the previous owner tried fixing a wobble issue (which some of the CV lenses have) and couldn't get the front badge/ring off and ended up scarring it up pretty bad, i filled it in with black ink and it's 'ok' looking, it's the ring that says 35/1.7 etc.
I'm only thinking of parting with it for silly reasons, mainly that it's a black lens, and my M2 has an oxblood covering, the black doesn't look as good with the chrome/oxblood as a silver lens.
Also, unless you need the speed, the CV 35/2.5 is amazing. It's about half the size of the 1.7