I was really excited when I learned of the new Sony A7r primarily because of what it had to offer in terms of its size. Let me explain my dilemma.
I really love the Nikon D800 system and various lens offerings. Of course there are a few I wish they would adopt from Canon but that is besides the point. I travel a fair bit for work and sometimes I get to go to nice places and schedule an extra day to do some photography.On the rare trips where there is a fair bit more free time with a nice photography venue (e.g. the Rocky Mountains), I will take a lot of gear including a tripod and check my non-camera luggage. However most of the time I want to go light-- carry on only. So I had had two options-- take a micro4/3 system (camera and lenses that cover 14 to 600mm -35mm equivalent--which of course has a lot of limitations) or my Nikon with the 24-120 VR, 70-200/4 VR, and then one or two primes based on where i am going (e.g. Zeiss 18mm/3.5 distagon, Zeiss 50mm makro or Nikon 105mm micro, etc).
So along comes the Sony A7r and I think this is the perfect travel kit. So now i have the Leica M 16-18-21mm, Sony 35mm/2.8, Leica 28-35-50, Nikkor 50mm AIS, Voigtlander 75mm/2.5, Leica 90mm/2.8 and a Voigtlander 90mm/3.5 in Nikon mount (which in many ways I prefer over the Leica 90mm) and if needed a Zeiss 135mm Nikon mount. I think the Leica 16-18-21 is superb on the Sony whereas the 28-35-50 is so so. I love the Voigtlander 75 and both my 90mm options have their pluses and minuses. The zeiss 135mm is a killer.. amazing… but it is big and heavy..
So now i need 3 different adapters and 4 different lens formats… Leica M, Leica screw mount, Nikon, and then of course the non-adapter Sony format. I find when changing lenses with all the different formats, I sometimes get confused (briefly of course) pulling off the lens vs lens and adapter, covering the rear with the correct cap… etc.. So now my bag is getting a bit larger than i had originally anticipated and lens changes a bit more complicated. Not sure if anyone else is feeling this way. I am hoping with some of the Sony new lens offerings, I can get down to using the Sony format and perhaps one adapter format to get a good travel kit.