Very late to this party, hopefully, I can still share some information.
The absolute biggest difference between MF and 35mm is without a doubt the quality of the file. Sometimes it almost seems like it is cheating when I am going through files in Capture One. Ideally, I would love to shoot everything in MF, but since ISO50 is not always ideal for some of my work the Sony A7RII gets used. I would ask you what your style of shooting is, everything is slower and a bit more technical with an MF camera. 99% of the time I am shooting with it it is mounted on a tripod, this is not that great of a set up for run-and-gun unless it is a very bright day out.
In regards to the files themselves, besides the obvious increase in DR, there is a certain look to the files. I think it's a mix of the depth, color accuracy, and sharpness. The amount of detail you can pull from the shadows and highlights is very impressive.
All that being said if I were to show you a 5x7 print from either the Sony or the MF, most would have a very difficult time noticing much difference. For me, the biggest reason I jumped into MF is that I regularly produce work upwards of 7 feet wide from a single frame.
If you need any more information let me know. I am shooting with a Phase One IQ260.