Viewfinder
Sony also missed a trick here, that they could still recover! The contax had a viewfinder that was positioned on the back of the camera. It protruded just slightly off the top left. This gave a great position for the eye, so your face was not pressed into the back of the camera and your left eye was free to roam.
There is space for an after market EVF that attaches to the RX1 hot shoe. But instead of rising up like a plastic monster, went down and across to the left. I don't need it to cantilever. Just be solid, fixed and not get destroyed with going in and out of a bag 1000 times. Only problem is the flash button, but I would never use this. This would give a much better perspective to the photog.
See this old for sale post for an example:
http://forum.getdpi.com/forum/gear-fs-wtb/7486-fs-contax-g2-setup-45mm-planar-tla.html
Lens / Sensor Matching
Lastly to throw the cat amongst the pigeons, I am pretty sold on the idea that the lens and sensor must work in harmony for ultimate IQ. I won't be at all surprised if the RX1 gives better IQ than the A99 in certain situations. After shimming my back to match the lens on my Alpa I am sold on the idea that this is how to extract the last bit of IQ out of your setup. So I think Sony has done something right here by having a fixed lens /sensor combination. I would be OK paying $2,700 for a couple of RX1's. People regularly pay that for one Leica lens. I pay that for one Phase One LS lens. The advantage is that if one RX1 broke down, I could still carry on. I would be ok owning a RX1/35mm and a RX1/50mm for example. As long as the rationale was because the lens matched the sensor perfectly.
Having said that please don't read this Phase One. I can't afford to buy a new P40+ everytime I buy a new lens. There is a price point where this is ok!