Sony A57 vs A65 noise

Pixel level noise is very much better (as it should be), the image level noise, as many people have found is as close to identical as makes no odds..

DxO measure noise in terms of  'Screen' and 'print'   (Screen = pixel, Print = image)..

If you look at any current gen 24/16 MP sony sensor's in print size, you can see that in terms of measurement variance they are too close to call.

Nex7 vs Nex5N

Or A57 vs A77

And DPReview show the practical side with the A55/A77 in the A77's review as I stated previously..

http://www.dpreview.com/reviews/sonyslta77/19

The biggest issue is finding 'comparable' data.. most lab image comparisons fail to even match the same camera exposures leading to more light getting to one camera or another, or relying on RAW converters by setting key RAW conversion parameters to zero thinking that makes things comparable.. or ignoring the obviousness that differing levels of RAW pre-conditioning occur..

It's been flogged to death a million times.. the SLT mirror, that makes a difference.. pixel size for comparable generation sensors, it's negligible unless you compare apples to oranges..