Agree. We actually agree on almost everything, except that one issue, which is whether or not calling the Adreno 225 insufficient is premature.
I take "sufficient" to mean that games on WP8 devices can run at equivalent quality settings, at identical resolutions, and at the same frame rates as on the competitions devices, preferably noticeably better on all three counts (because that would be a great way to grab more market share).
First take a look at this
GPU benchmark, comparing the MSM8960 (as in the L920 but tested on the SGS3) to the A6 (from the iP5). Notice that the iP5's GPU is often twice as fast in every relevant metric (ignore the onscreen tests, as the iP5 will always perform better in those tests due to having a lower resolution display).
You can rightfully argue that WP8 isn't burdened with many of Androids inefficient software stacks, but consider that games tend to bypass most of those inefficiencies. OpenGL provides Android developers a very direct (and exceedingly well optimized) route to their GPU, just as DirectX does for WP developers. I don't doubt that a L920 could better the SGS3 in this benchmark, but I don't see it getting anywhere close to the results spit out by the iP5. IMHO that difference is just to big to overcome with software engineering alone. This is disappointing, because both devices hit the market at roughly the same time.
I wouldn't argue my position in an academic paper, because as you say until you actually measure it nobody can really know, but still... that difference must be almost impossible to overcome, no?
BTW: really liking this thread... high quality discussion!