Don't fret buying the old single coated C lenses, I kind of prefer them...nice look to them as regards to image quality and the chrome just looks nice! Zeiss lenses just don't seem to need multi-coating as much as some others, the 80mm and 150mm that I have are just contrasty enough. The wide angles on the other hand can benefit from multi-coating due to many more elements and the higher risk of including a light source in your photo.
As already stated, the aperture change is a pain, but you get used to it. Also the shutter on old lenses need checking as they get sticky, but a CLA on these old Compurs will have them good for another 40 years.