No way are we dealing with 400 cycles with the ESRAM right there on chip. Anything is slow in comparison to the cache, but I think you're horribly exaggerating how quickly GCN is equipped to get the necessary information back in there to handle the GPGPU task. This takes me back to an earlier point. Simply because the PS4 has these extra optimizations, you're almost essentially discrediting GCN architecture to the point that you make it seem like it simply isn't effective at doing precisely what it was designed to do in the first place, which is handle GPGPU tasks alongside graphics related tasks, and do so effectively.
Now, we may not agree on the minor details, but I simply cannot agree with you so strongly disregarding the ability of AMD's GCN architecture to accomplish the very thing it was designed to do. With some of the things you've said, and since many PC GPU, well, all, do not have PS4 type optimizations, you're beyond the point where you're underestimating the GPGPU capabilities of the Xbox One architecture, you're effectively now underestimating and indirectly labeling as flawed AMD"s entire line of GCN class GPUs. It may not handle it as effectively as the PS4 will, but the Xbox One can most definitely handle GPGPU. And GCN hardware that exists right now on the PC can handle GPGPU, or compute tasks such as TressFX just fine. GCN was designed to handle these things, as was the Xbox One, even if not to the extent that the PS4 was. And one of Microsoft's key takeaways to the developers they briefed on the Xbox One architecture was to start looking at GPGPU. That's not something you say to developers if your hardware is somehow not very well equipped to handle it, or I would hope not.
Just my 2 cents. But this chat was very informative, and while I'll be heading off to bed. We'll def continue this tomorrow. Good chatting with you, dude. And night everyone!