Seepaert, none of the solutions you suggest can be considered as a replacement to a regular lightweight and cheap field camera. A digital back has less resolution, is extremely difficult to focus (most suggest using a laptop to verify focus) and needs time consuming workarounds to deal with colour casts caused by shifting. They also cost as much as a very decent car. Using a 22 megapixel DSLR with a LF camera needs very expensive digitar lenses and is again almost impossible to use with movements due to the tiny screen. Stitching is possible but not with moving subjects including leaves swaying in the breeze.
Etc, etc etc.
The solutions are out there but that wasn't what the OP asked.