Some are reporting equivalent IQ when the 5D2 image is cropped to match the 7D FOV.
At low to mid ISO...nonsense. They're probably sharpening the files the same or not sharpening at all, and basing their judgement on that mistake. And/or getting hung up on photon shot noise that disappears with a light NR pass.
That said...the difference is small to nonexistent unless
you both crop further and print large. I've got 20" surfing prints made from 8-10 MP crops out of 7D files. Never would have made it that large with a 5D2, 5D3, or 1Dx (given the same lens). Anyone who questions that the 7D provides extra reach can go ahead and try to make 20" prints from 2-3 MP FF crops. The difference in IQ will be quite obvious.
But...I've only rarely had to both crop further and print large. If you're just trying to match APS-C's reach...not any further...then the differences just won't matter, especially when printing 8x10, 11x14. But even at 20" you can get away with it. Wildlife and sports do not stress resolution like a landscape. It might sound hard to believe, but 8 vs. 18 MP isn't that big of a deal in a 20" print of a surfer or deer, given proper post processing.
So yes, crop sensors really do add reach. But the differences are only apparent under extreme circumstances.