You should definitely consider a vintage folder (unless you've decided that you want to spend the serious coin that the Fuji GF670/Voigtlander Bessa III requires). Look at the certo6.com site to get an idea of some of the models that are out there, and the formats. I think there's a fair amount more options in 6x6 and 6x9 than in 6x7. I think a nice compromise between capability and size is one of the Zeiss Ikon Mess Ikontas -- either 6x6 or 6x9. These have uncoupled rangefinders, but work quite well, and are available with Tessar lenses. Jurgen (certo6) is a big fan of the Agfa folders, many of which have uncoupled RFs and 4-element (Tessar design) Agfa lenses. The Certo-Six (that's where he got his website name) is a very nice coupled RF 6x6, with a Tessar and Synchro-Compur. A real sleeper. And the old Mamiya Six (not to be confused with the newer one you mentioned) is a very nice camera indeed -- internal focusing!