The biggest takeaway I get form this is that Opera has done this before but never shared it with the outside world. At a minimum we know that the kind of speed up SDPY proposes is possible and apparently used in production systems.
Of all the parties Google should listen to for SPDY feedback, Opera is probably the top of the list. It looks like Opera took it quite seriously and shared a lot of good work with us all, and I thank them for it. I'd say their point about the asynchronous headers is one that requires serious addressing ASAP. For one example, is it valid to push down a header redeclaring the encoding of the response at the very end? What would that even mean? It's a good point.
It seems likely but I can't prove that behind a couple of statements like "As defined the feature is not powerful enough to push non-request related content (such as new RSS items)" is the fact that their approach does do it (and possibly had to add it on later only after they discovered it was a problem), but the document is very carefully written strictly as an examination of SPDY, with no braggadocio I can see at all or any trace of marketing beyond the initial statement of "Hey, we've done some stuff and here's some observations we are in a position to make".
(Again, my compliments to the chefs.)