I had every intention on getting the 1520, but then came to realize, all that extra power will be of little use. Decided the camera on the 1020 had more appeal. Then I went into an AT&T store and held the 6" Samsung and I'm glad I didn't wait for the 1520. I have big hands and its just too big. Alot closer to my 7" tablet than I imagined.
I will be interested to see if there's any reason to really want a quad core with WP 8/8.1 in the near future. And that's coming from a guy who usually wants the newest/fastest stuff. WP just runs so efficient.
My main appeal to the 1520 is the fact that it has expandable memory, 64gb micro SD support. There is only one thing I hate about the 1020 and it's the lack of storage, same with most the other top end Nokia phones. But holding a 6 inch screen phone on your hand is a bit ridiculous. A 4.5 screen is perfect size.