The Leaf AF-II 10 seems to have the widest sensor ever made for use in a digital back. At 56mm wide the sensor should be great to get the widest horizontal angle of view from any lens. I have no clue if it works well with the Rodenstock 23mm and or the Schneider 28 but I don't see why it shouldn't.
All Dalsa 6um sensors should work very similarly in terms of color cast etc.
Early in this thread Robb reports using the 28mm with great success:
http://www.getdpi.com/forum/564359-post12.html
I'm also considering this back, the only angst I have is if I'll think it's okay to work with the 3.1:2 ratio or if I will hate it. I shoot both DSLR and MF, and I surely prefer the MF's 4:3 to the DSLR's 3:2, but well, you can always crop, and in the cases you do want a panorama perspective this is one of the best sensors you can have, with an incredible price/performance ratio. I know many prefer the simplicity of the P+ series user interface, but for tech cam work I'll choose Aptus user interface any day. So this really is a great tech cam back, if you can live with the 3.1:2 format.