I can tell you the 24 mp of the NEX-7 is more than enough. I am finding my computer handles the files just fine with no upgrading.
Greg, I'm using "cheap" Leica Summarits on my NEX-7 - the combo of Leica glass and 24 mp is quite incredible. In a pinch I can use my Nikon glass with the Novoflex adapter, but then the package becomes quite noticeable - large and a bit weird. The first time I mounted a 180 2.8 on it I burst out laughing. A NEX-7 with a 50 Summarit is quite pocketable and very, very discreet. Would of been nicer with simple M9 controls, though. If I want WA I have to shoot with ZF.2 Zeiss 21 or Nikon 24 2.8 Ais and with a crop sensor it's still not all that wide. All that said, though, I spent all day yesterday with my D700 and the Zeiss 21 - shooting with old friends makes photography fun and intuitive.