I think that the compression of the tone curve is mostly irrelevant, since the part of the resolution that is lost is completely swamped in shot noise anyway. The thing is that this compression is almost certainly done in the ADC itself, and doing so is a very smart move.
Sony uses column conversion, meaning they use a lot of ADC's in parallel. This, in combination with some other tricks, seem to get rid of most, if not all, pattern noise and leaves the low read noise. All this is resulting in the great dynamic range of Sony sensors. A problem with having so much ADC's, is that they have to be simple. And simple they are. Sony uses the most basic of ADC's, where a voltage that is ramping up, is compared with the analog voltage out of the sensor. So called slope analog to digital converters. A problem with these is speed. For 14 bits, such an ADC needs 2^14 clock cycles for each conversion. when using say a 400MHz clock, this means 41us per conversion. Sounds fast, but they must perform over 6000 of such a conversions for each image, stretching the conversion time to a bit ore than 0.25 sec. This is a bit slow, for high frame rates, but also for live view.
The slope, or voltage ramp, going into the comparator is generated by an analog to digital converter, meaning that the shape can be made as desired. Sony uses a variation of an exponential slope (the compression). This cuts the conversion time down by a factor of eight (2^11 in stead of 2^14). Now the total conversion time is slightly over 0.03sec. Great for live view.
It might very well be that this explains why Nikon live view is as poor as it is (line skipping to reduce conversion time), compared to that of Sony.
And the elegant thing is that this compression is not really costing much, if anything. 14 bits are needed for he dynamic range. But signal to noise ratio, when light is hitting the sensor, is not only determined by the ADC and read noise, but also by a property of the light itself; shot noise. Say that the a7r sensor has a full well capacity of 60000 (optimistic). Such a full well capacity means that at maximum illumination, the snr is sqrt(60k) is approximately 245, which can easily be resolved with an 8 bits ADC. so with 11 bits, there is room to spare. That is the thing with shot noise, its level goes up with the signal, not just as fast, but it goes up. So the 14 bits are needed for the deep shadows, but once there is enough light on a pixel, you do not need them anymore.
It would indeed be nice is Sony would also allow you to use all 11 (compressed) bits, without the second part of the conversion.
Sorry if all this is a bit technical, I do not know how express the above otherwise.