I owned the CA20E version of the S12. It wasnt a bad car at all. I had it for a little over 6 months. The rear suspension is the same as a Z31, the front is almost the same as the Z31.
http://www.club-S12.org is the site to hang out on if youve got one, or are looking at them.
Mine had roughly 200k on it, I did replace the brake rotors, and went to hell on the new ones with no warping problems. The car had good snow manners, I have a feeling with a good set of tires it would be quite good in the snow (not that you have to deal with that, just saying) It was slow as hell, I assume the turbo or V6 version might be acceptable.
Im sorta looking for one, if you decide not to get the one you are looking at I might be interested in the contact info.