Speaking practically, and from experience (having used R lenses in similar manner on digitals that do not have image stabilization) it actually *is* rather tedious. Focus peaking helps, but the reduced image on an EVF will often portray areas of high contrast as in focus, when they are not. To get around this, one has to magnify the image. Try a 10x mag looking through a 100mm lens...you'll get serious camera shake and you'll lose track of the subject, not to mention framing. Add in the complication of a manual diaphragm and it's not a pretty picture.
Other cameras also have flip LCDs which make tripod shooting much more enjoyable.
If I wanted an M, I would shoot it as a traditional M - not with the EVF, and not with the grip, and not with R lenses. It's good that people who want that capability can try it, but iMHO they will ultimately be disappointed. The A99 is a far better platform for adapted R...people in that market segment probably can afford both anyway.