One important consideration is that it is still easy to get a K-1000 serviced, unlike an MX or KX. When I went looking for a body to replace my dead ME super I decided against looking for an MX or KX for that reason. Had I not found a deal on e-bay for my K-1000 I probably would have bought a ZX-L and used my M and K lenses on it.
I have always liked uncluttered viewfinders so I don't miss not having info in the viewfinder. I almost never used depth of field preview or the self timer. The only thing I might want is mirror lock up. Yes I know the shutter button trick, but I would use mirror lock up with a cable release which would make the trick awkward at best. The K-1000 handles like the spotty I used regularly for 20+ years. BUTCH "Each man had only one genuine vocation - to find the way to himself" Hermann Hesse (Demian)