I guess you won't regret if you decide to choose the Tele Xenar.
It's a blue blood Sonnar derivate, quite famous for its qualities.
Present day Schneider lenses are out of reach for most of us, why not give a good chance to a vintage one?
Your 135mm has been praised over and over in countless blogs and fora, often preferred to the similar CZJ Sonnar of identical focal/speed. You can find out by yourself if it's true or not.
For everyday use I don't know if I would choose it in place of the Pentax-M... but for a Single In you can forget about the inconvenience of mounting and removing the adapter. You can do it once, and then shoot, with no concerns about dust, etc.
You might even shoot in AV (which is very practical, IMHO).
If you liked an old Tomioka-made fifty, I guess you'll appreciate the Schneider too.
If your example has no hidden flaws, I'm quite sure you will prefer it over the Chinon. Tomioka made/designed 28mm's and 135mm's seem to be inferior to their impressive fifties.
The choice is yours. I'm just giving some preparatory info. Kind of sharing with you some potentially useful homework
One last thing. I really like the way the Schneider looks. Especially the elegant hood.
It doesn't help taking better pictures, but it makes the process more enjoyable
Last edited by cyberjunkie; 09-22-2018 at 06:23 PM.