There is no such thing as a "Sony feel", sorry. Sony makes a ton of different stuff, and much of it has little in common with the rest of it. So, whatever past experience you had with Sony, it's meaningless here.
The A7 will cost about $1600-pretty sure that's body only. Current adapters will allow any m lens to be attached.
That really leaves only one question: how does it do with my ZM 18? The 5n takes quite good pictures with that lens, so it's no foregone conclusion Sony is going to bungle it.
Also, the A7r has a different sensor, which will either be better or worse.
In January a bigger model, still much smaller than the 6D, will be introduced with IBIS, and the ability to focus from the sensor.
I'm no fan of Autofocus, but what this means is that you will be able to autofocus your M lenses to some degree-only on that January model. That camera will certainly be lighter than the M240. So it could be a real contender for stealth Street shooting of extreme quality.
It really doesn't matter how you "feel" about Sony, the only thing that matters is how good is the gear. I would think by now they have some credit for innovation coming, but not much around here :-(.
The nex 5, 6, and 7, are excellent cameras capable of superb results in a small form factor.
The RX-1 is a new benchmark.
Regardless of local snobbery, I like Sony right now. 🙂
Leica, on the other hand, still cannot even get their product into shops. A year after announcement m240 still basically unavailable.
On top of that, leica is blind to huge market for smaller sans-rangefinder live view EVF body for m lenses. Something the size and weight of the original Leica. Price around 5K.
But Sony may push them there.