Whoa, Colin, I don't see you shooting in color too often, very nice! To be honest, if I had my way, I would get the Zeiss, but it's really expensive, and I just now bought an R-D1 and don't feel so flush. Still, maybe I'll do it. When I first got deeply into RFs about eight months ago, literally the first thing I shot with was a Contax G1 with 28mm Biogon, and while I eventually gave up the G1 (I didn't enjoy using the AF and ended up with an R4A), I still miss the hell out of that glass. My favorite lens I have used so far. So perhaps it's worth the investment.
Someone put one on the classifieds for some insane low price yesterday and it was gone in seconds.🙁