If you know anyone who has mono-block amps, this is taking it a couple of places farther. If all stages are isolated, they can't have any crosstalk or other influence over each other. If one channel is sucking a lot of juice, it won't affect the other the way it would if they shared the power supply. If they do this in the preamp section too, it sounds like they really want to make something special. The only thing they can't get away from easily is sharing the power service ground.
It's not new, it's just their version. I have an old Conrad Johnson MV-45 and I had them e-mail the schematic- it's one channel and only the B+ and chassis are shared. The ground planes are separate.
That said, some of the receivers, pre-amps and DVD/CD players I have been seeing show S/N of >100dB. In most cases, no noise will be heard. I don't know how much more quiet they can make it- the best S/N I have seen lately is 130dB and for all practical purposes, that's more than quiet enough.