"Actually, the real pain comes not from ESRAM but from the small amount of it. As for ESRAM performance - it is sufficient for the GPU we have in Xbox One."
I've been saying that for months. Now every time i need to explain that to someone i can just quote this guy as a reference 
It would be interesting to know what sort of real world performance advantage developers see between the PS4 and X1, assuming perfect conditions. They tend to dance around the specifics of that issue. The figure is definitely somewhere between 30 - 60%, but past that it's incredibly hard to tell.
Personally, I'd bet on about 40%. A very significant amount, especially for 1st parties, but small enough (relative to equal development time) that the PS4's 3rd party advantage should remain as IQ and stability boosts.
