Yea I was going to make some commentary here that it's going to be better if they go fast than wide. Once they go wide, everything has to increase in size to accommodate or bottlenecks will end any advantages you gain by going wide and such you lose real-estate for other silicon requirements.Well I've thumb sucked a new theory based on absolute hearsay
With the possibility of 1.8ghz GPU part it might mean they crunched the numbers and came to the conclusion that a higher clock and smaller chip for the GPU worked out better.
Leaving them more silicon for other special sauce such as possible Ray tracing tech.
Increasing the clockspeed drives improvements across the board, this seems a better bet to me.