I'm going on a limb here answering so take what I say with a grain of salt.
While I don't have a RM3D and don't shoot architecture I have owned a Schneider 72mm for several years. One aspect of telling how pleased I am with this lens is its longevity. I this lens several months after getting my WRS and have been happily using it since.
Remembering I shoot little other than landscape this has been one of my most used lenses in my 2-lens kit. The image quality is very sharp and clean both on a P45+ and now even more so on the P65+ (I just completed writing a 3-part comparison on the P45+ and P65+ on a tech camera on my blog). While the image circle isn't as huge as my short barrel 120mm it still is good out to 15mm left and right. I think I might be able to go slightly further however I just haven't had the time to test it that far.
My feeling is that color cast is a given on a tech camera therefore you shoot a LCC prior to each image capture. That said, I have found the 72 to be very forgiving.
So to sum it all up - I have no experience with a Rodenstock, RM3d or architecture photography. I do however have experience using the Schneider 72 and like it a lot.
Just my 2¢ worth
Don
I can't close this without the following recommendation. It's fine to solicit opinions however when the rubber hits the road only you can tell what's best suited for you; so make every attempt to try both out first. Okay I had to say that and I feel much better now...
Don
