I was actually thinking of both specs to a degree. On the one side, when did Dolby start to offer manufacturers enough detail (either a finalized or draft spec of PLIIz or even just a white paper and schedule for development) to justify including the support in hardware? On the other side, how long ago was the hardware for the R-972 finalized enough to make adding two more analog channels (or adding hardware to integrate a second zone into the main system) practical?

As you say, short of somebody like Lexicon adding support to the MC-12 (which has the advantage of significant flexibility in output channels), it may be a while before we see 9.1 hardware available to support PLIIz and rear surrounds simultaneously.