Thank you for your reply from which I learned a lot. I started many years ago with Leica M3 and transitioned to Nikon F because of much wider lens range. As I got older, weight became an issue, and I tried several mirror- less systems, but was never satisfied with image quality or quirks of operation and viewfinder experience. Finally, along comes the Sony A7 series (especially the new 7R11) with a viewfinder that helps my aging eyes and a form factor that takes pity on my back. Having relatively light weight Zeiss lenses available is a big plus, although I would jump on a Zeiss 135 f2.8 in a heartbeat. I just wish Sony would iron out some menu bugs, but they seem responsive to suggestions, so I am hopeful.
I very much enjoy your reviews and appreciate the amount of detail and comparative information you provide. Many thanks.