With the Zeiss 25/28mm finder atop an M6 or MP, I'm ready to shoot my 24, 28, 35, 50, 75, or 90mm lenses. And if I use my 0.58 body, I even have a choice of internal vs. external finders with my 28mm. The only thing left out is my 21mm, which requires a change of finders. (Solution: leave it home.) So although the R4 still is tempting, I seem to be covered with my present gear. I resisted external finders for a long time, but since then, I have come to like them--at least the better ones.
It could be that this thread really belongs over on Tom A's area, since Tom was the driving force behind the creation of the R4. It is clear from what Tom has written elsewhere, that he strongly felt the need for a wide-angle Leica-compatible RF, without the need for external finders. In fact, it was Tom who thought of the idea of mounting a goggles on the 21mm Super-Angulon, so that almost the whole 21mm filed (22mm in actuality) became visible using the Leica's 28mm frameline. Same idea as using goggles to make the 35mm field appear within the 50mm framelines of the M3. The goggles mod on the 21mm SA was carried out by Reinhold Mueller, based on Tom's design.
So I think there is a lot of support for wanting the framelines within the camera, rather than external. No doubt this is more important for those who work rapidly, like PJ types and street photogs--those who are more apt to lose a finder in the heat of the battle--and maybe a little less critical for slower working types like myself.
