No camera can reliably deliver much over 100 lp/mm ON THE FILM with any lens, simply because film location is not good enough. I have seen 125 lp/mm more often than not with a 75/2 Summicron and I have never seen better. To get the vaunted Zeiss 200 lp/mm you must 'bracket focus' which is hardly realistic in the real world.
The Zeiss lenses are very, very good (I have tried all except the 85/2). I would not hesitate to use any of them for the most critical applications -- and I have tried them on Zeiss Ikon, Leica and Voigtlander. My wife Frances Schultz and I have reviewed them for Shutterbug magazine; she has reviewed then for Black and White (UK); and we have also reviewed them on www.rogerandfrances.com, but unfortunately it's $2 or you have to subscribe to read the review on the site.
At this level, considerations such as size, weight and handling matter more than image quality, and the only reasons I would hesitate for an instant about Zeiss lenses is that I prefer more speed (such as 35/1.4) and obviously they have not the decades of proven durability that Leica lenses have.
The former (speed) cannot be challenged; the latter (durability) is probably an unnecessary reservation, because I have used Voigtlander lenses hard since they came out and have yet to have a problem.