Getting ahead of the curve on this one . Assuming that the speculation on the M9 is close...FF,18MP,+2EV ...cost near the D3X...special order only for months and depreciated resale values of the M8/M8.2 ......a lot of users will be building kits with both the M8 and the M9.
This will of course create the opportunity to debate and speculate over the ideal lens kit for your M8s. This is already starting . This is further complicated by the discussion of UV/IR filters.
It might actually be better for me if they still used the filters. Otherwise a m9/m8 may require changing filters.
But those are the hardware related issues (always fun but only part of the story). What about the files and associated IQ?
You hear of numerous situations where people have mixed files from different systems ......wow I can pick out the Leica files make the others look sick? This is extreme when you mix MF with 35mm(see Salgado s book on Africa with m6/R6 and Pentax67 ).....you can see it when you mix say .Cr2 or .NEF files with the Leica DNG s .
Now you may have 10MP files mixed with 18MP files and using different camera processors. The closest I can come to this is the DMR and the M8 ..they look alike but on some images you can pick out the DMR files . For this reason I try not to use the Nikons with the M8s on the same assignment. But I know others seem to.