I read this article on ISO invariance:
http://improvephotography.com/34818/iso-invariance/
I get it but it would seem you'd need a lot more than 14 or even 16 bit resolution in RAW. Basically each ISO step (e.g. ISO 1600 to 3200) needs an extra bit (because you're halving the intensity or photon count, if you like, going from 3200 to 1600). So if you want to shoot at ISO 100 and then boost it to ISO 6400 in post-processing and still want say 12-bit colour at ISO 6400, then you'll need 12 + log_base2(6400/100) = 12 + 6 = 18 bit colour.
It's the same as if you want to record audio but don't want to worry about levels. You record in 24-bit to capture quite (-45dB) signals at 16-bits for the final master.
So I don't see how this ISO invariance could work as well as amplifying the signal as it's collected at the sensor.
