Sorry, did not seem to be harsh, late night.
More info:.
I have used the 35mm SK for years now, on the P45+, IQ160, IQ260, IQ150, IQ180, 3100, and 4150. On the CCD backs, even up to IQ180, the 35mm SK was
an excellent lens, light weight, and with the CF shift able to about 8mm. On the 3100, due to really harsh Lens cast issues I only tried it once and then moved to the Rodenstock 32mm. The color cast IMO was just too damaging to the image. I never sold the lens, and when I upgraded to the 4150, decided to try it. I was pleasantly surprised by the results. At F 11 (issues of diffraction and the like don't bother me as much but I am a huge fan of fine detail), the 35SK with the CF was really a great lens. It's not as sharp as a 32mm Rodie but it's close enough that I can easily sharpen it in post to get where I want to be. The 32mm Rodie, is massive, much more delicate and has huge distortion issues (never have understood why more photographers don't notice it. As you approach the edge of the image objects towards the edge become flattened and elongated and if you shift it all the effect is worse. I have seen this same distortion on 3 different 32mm Rodies, so I feel it's just part of the lens design. The 35mm Sk will not show this. But it also has really no room to shift on the 4150 at all. So for me it's a great lens to use for a pano, where I am on center the entire time and just panning across the scene. Without the CF, you gain 2 stops or so of light, but you will start to see color cast issues more noticeable and issues of vignetting, but the LCC process will take the vast majority of that out.
The 60mm Schneider, really is an excellent lens on the 4150, on center or shifted to 15mm. I have the CF for the lens, but have found that most times I no longer need it. I still will take an LCC series at the beginning of a shoot, but no longer take an LCC after each frame, as the 4150 just has no color cast with this lens, thus all you are doing is correcting light falloff and a base set of LCC's will fix this.
The 90mm Schneider, I have not used, but have read plenty of reports from owners of it that use it on the 4150 and have experienced the same results as the 60mm.
The 120mm Schneider, (one reason I would not consider moving to the XT) is just one of those lenses if you can find it, and can afford it, buy it. Schneider only made these towards the end of their digital lens run but it's optically a wonderful lens. Again light, tiny and as sharp as any optic I have used. You can shift it well out to 20mm. As any medium telephoto lens, it has a limited DOF, some of which can be regained with tilt. It needs no CF and color cast is non existent as is light fall off, net no LCC will be needed. You will need a back extension if you use an Arca system, Cambo apparently makes a mount for the lens without a back extension, actually they make it both ways.
I have also been told that the 28mm Schneider, which was very limited on the CCD backs, and trouble some on the 3100 seems to perform well on the 4150 also.
All of this is based on my actual use of these lenses in the field.
Sincerely
Paul C