that 13% for the 6 gb 1060 over the 8 gb 480 was compiled from more than a dozen reviews across the web. i literally combined all the reviews and computed an average total % over all the games reviewed from the various sites. can't think of a more unbiased way to get the number than that. takes a long time to compile all that data and i stand behind it 100%. one site might be higher and another may be lowe, but when they are all combined a very solid performance picture is built.
but go with whatever you feel like i guess.