Should Your Next Camera Be a Sony?

Willows and cottonwoods in late-afternoon light, Yosemite. The outstanding resolution of the Sony A7r allowed me to make a 40×60-inch print that captures all the fine detail of this image.
I don’t review or even talk about equipment very often, but I reviewed the 36-megapixel Nikon D800E last summer because I think it’s such an important, game-changing camera for landscape photography, with exceptional resolution and low noise. Like many Canon users, I’ve been waiting for Canon to offer a competitor to the D800 and D800E. Rumors keep circulating about a 40-megapixel Canon camera, but so far nothing more substantial than a rumor has appeared.
Then last fall Sony announced their new full-frame, mirrorless Alpha A7 and A7r cameras – the A7 with 24 megapixels, and the A7r with 36 megapixels. The A7r uses essentially the same sensor as the Nikon D800E (though Sony says they’ve improved it). For a Canon user like me, the A7r was intriguing because some readily-available adapters could be used to mount my Canon lenses on it. The short distance between the sensor and the A7r’s lens mount makes it possible fit an adapter between Canon or Nikon lenses and the camera, and still be able to focus at infinity. So I could potentially get the resolution and noise control of the D800E without having to make a large investment in new glass. And the A7r seemed reasonably priced at around $2300 (though adding an adapter and battery grip brings it close to $3000).
But I had some big questions. The A7r is a mirrorless camera, so would I miss a real, optical viewfinder? How well would my Canon lenses function with the adapters? And what about “shutter-shake,” and other potential problems that I’d read about online?