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I came from FF to mirrorless, so I ended up w RX1/A7R. However for wildlife I prefer apsc, even more m43 for the 1.5/1.6 to 2x multiplier... But still mirrorless is weaker on that side due to limited lenses. If you want the FF dof for portraits, you can also use Metabones adapter... Manual focus is much easier w/ mirrorless esp if you are looking for Zeiss lenses...
I have just taken the first tentative steps into FF with an A7r to accompany my beloved EM1. I agree with Ray that the ability to really push raw files in post is what I really like about FF as well as the extra detail at wider angles.
I didnt even consider a DSLR and I am pretty certain I wouldnt like them. I have never actually owned a DSLR with the EM5 being my first interchangeable lens camera. But when I have used them, I really miss the EVF with all the electronic gizmos that come with it that I rely on pretty heavily. I also find dials and aperture rings pretty useless. The A7r has an EV compensation dial which I find pretty irritating (what is with that anyways?). My feeling is that especially as of today, if your first camera is a mirrorless, it is unlikely you will want to move to a DSLR.
Well I have gone to the dark side and bought a Sony RX1r, for a job I am working on at the moment, very interesting camera
I think the lens is good but I also think it is the magic of the interface with this chip.
By the dark side you are right it is rejoining the Sony Death Star and buying another camera with a fixed "35" lens. I mainly bought it to shoot high quality back plates that I normally shoot with my Nikon 800, but I wanted something that no one would notice even on a tripod. I must say I was very impressed, it work perfectly for its mission and I also came away with loving the files, and will probably use it more and more as my grab and go camera, sharing duty with the GR. While I am sure it will be fun to make B&W images with this camera, it almost seems like the wrong use since the color is so good.