I found this interesting....seems the same developer who started this rumor came back to Neogaf to correct this misinformation. He was making reference to Development Time...not hardware power at all. Sorry if old.
From Neogaf http://www.neogaf.com/forum/showthread.php?p=80542977#post80542977 :
"I think Adrian should jump into the conversation. He does it all the time in his blogs.
Here I am. So...
1. I am not doing a damage control, but I do want to clarify one thing. But first, yes, devs I know -- and as someone has shown it before in this thread, some other devs already talked about it too -- claim that there's 50% speed difference WHEN DEVELOPING in cross-gen/next-gen PS4/XO games. So there we are, I said it and I stand by it. Notice: WHEN DEVELOPING. It'll become clear in a second."
More and more lies being cleaned up.