I've used the 135mm in Contax RF mount -- all three versions (original black and nickel, heavy chrome and lightweight postwar alloy). It's really a sweet lens.

I've also used the f/4.0 and f/2.8 Olympia versions in Contarex, and both are excellent lenses. The f/4.0 version likely is nearly identical to the final Contax RF version.

I've also used the f/2.8 version in Rolleiflex QBM and have found it to be an excellent performer. I haven't used it for architectural shots, so it's likely that I haven't noticed any pincushion distortion.

For $159, I think that you got an excellent deal.