If you were looking to do landscapes (mostly wide-angle), what DMF kit would you pick if the objective was to minimize cost while still being capable of better quality results than state-of-the-art 135 format digital (D800, A7R etc.)? By better quality, I mean essentially more dynamic range and resolving power at base ISO.
I am coming a bit late to that discussion, sorry. I did the following:
-used a Sony A900 for the past 5 years. I still have it and still find that its 24 mpix and lenses are sufficient for most needs.
-bought a Nikon D800 and some lenses about two years ago to test the competition. Found I did not like the lenses.
-tried a Mamiya RB64 and film (but not for landscape). It is quite capable and very cheap for what it is, but I did not want to go back to the hassle of scanning film.
-got a cheap, second-hand H3D-31. Found it to be already better than the D800. The resolution is the same, but the lenses are, to my taste, much better.
-on a day of folly, decided to get another MFD with an H3DII-50 (second-hand again). On landscape (your question), I find that it runs circles around the D800.
If you are on a budget, there are relatively cheap second-hand MFD cameras and lenses to be had. You can always get one, try it for a few months, and sell it back with little loss if you don't like it. But you are in no hurry: new cameras have been announced with a CMOS sensor, which in turn means that some second hand cameras will go down in price around summer. For example, I would expect used Pentax 645D to be had for little money...
Now, to your specific questions:
-more dynamic range: not really, but all cameras above have enough dynamic range for my needs.
-more resolving power: for the sensor, you will need something in the 50 mpix range to make a difference with the D800 and that may be above your budget. For the lenses, MF lenses are simply better than most of what is available for 24x36 cameras, especially for wide-angles. From hearsay, the only lenses that may be at a similar level for landscape may be the Zeiss 21mm f/2.8 and 15mm f/2.8 and the Sony 35mm f/2.8 FE.
Here and example comparing the Hasselblad HC 50-II with the Nikon 35mm f/1.4 G to give you an idea of the improvement.