So taking a back such as the Leaf II-5 on a tech camera and given the huge amount of stitching capabilities (if you are so inclined) with 4x5 lenses more than offsets what minor differences there are with the digital lens on a 9 micron sensor. Add to that the digital lenses are optimized for only F8-F11 where as the 4x5 lenses are optimized (lens dependent) anywhere from F11-F22 and a tech camera or view camera system like this for landscape work among other things starts looking very compelling.
Are you aware that you can rearrange the shift/tilt setup on these lenses. Have not done it myself but have heard of many others doing this with great success. Might solve some of your decisions.
I don't have the 45 PC-E lens but do use the 85 and 24 PC constantly, in fact on my trip to Zion in Nov those were the only two lenses I used, often stitching files together with the front shift capabilities, works great even though stitching is not my preferred method of visualizing a scene.
For sure if you end up going (either in the short term or long term) with just a basic MF camera like the Contax, Hassy, or Mamiya you will eventually have to focus blend to get your DOF on landscape work.