That nai benchmark is interesting, but I'm still skeptical. There are too many fresh users posting screenshots of unknown origin for me to jump on the "issue confirmed" bandwagon. I need a reputable source and not just for this benchmark but actual gameplay being affected. I certainly didn't see a problem with my own Watch_Dogs testing, hitting 3750MB VRAM without excessive stuttering. Beyond that, I can't say.
I have no problem with this being discussed but I see a lack of critical thinking and confirmed evidence of an actual issue. The job of these GPUs is playing games as good as possible and that is what all the reviews and my personal experience are showing. The theory of disabled SMM's and their distribution is interesting though, as that could explain different results for different people. I do recall the rather small debate on GTX 780's (which also had three SMX's disabled) on whether or not there is a performance difference between a chip where the disabled SMX's are evenly distributed and a chip where all three disabled SMX's are within a single GPC (see http://www.anandtech.com/show/6973/nvidia-geforce-gtx-780-review
). Obviously it wasn't a big enough issue with GTX 780, but that is not to say Maxwell couldn't be different.
So still not convinced, but there could be something here. I'm more and more inclined to think we will get an answer rather sooner than later, though.