Sure. The source was Sebbbi (TrialsHD main man)..
from this post,
http://forum.beyond3d.com/showthread.php?p=1738762#post1738762
He starts with saying how the EDRAM helped on the 360, then adds in what a 'memory scratchpad (or a big cache)' will help with..
No one actually knows the exact details of the ESRAM and how it's connected, and developers can't say anything at the moment (all under NDA).. I expect when games are shown at E3, we might start getting a feel for how large the gap is.
There are also other people (like ERP, a sony developer) that go indepth on why even they see some reason for the ESRAM in keeping your CU's running more efficiently, such that the 18 vs 12 CU gap may not necessarily be as large as it looks.
Saying all that, there is no way in hell the XB1 is going to be on-par with the PS4, I'm sure of that, but my expectations range from worst case 60 vs 30fps kind of territory to just a little bit worse (the reverse of what we have today with the 360/PS3).. I suspect the reality is somewhere inbetween..