NEX 6 better then the NEX 7 ?

The low light of the Nex 7 is pretty good as is. Is the 5n better? Sure but not by a huge amount. The Nex 7 still captures more detail overall - which may or may not be important to some people.

Also, iin terms of ability to crop, it really depends on what you are shooting. Events, parties, large gathering, isolation shots etc, these all benefit from the ability to crop extensively. If we're being sarcastic, then I could say, professionals NEVER have people randomly stepping into their shots ruining an otherwise fantastic capture. I take a lot of events and the ability to extensively crop my shots in post to remove arms, heads, shoulders and other things randomly popping into the shot is a massive godsend.

With the Nex7 photos, I can recompose the shot as necessary. Pros cannot control anything other than their cameras and waiting for the random person or vehicle to move out of your scene is not something that is conducive to certain types of photography. Or worse, not getting invited back for event shoots because you ended up being intrusive.

The Nex7 files are extremely versatile in this regard. If your shooting scenario allows you time to work the scene and control it, then it's not a big deal - in any other situation, being able to reframe and crop is a massive boon.

More to the point, the Nex 6 lacks the controls of the 7. Coming from the C3 and 5N to the 7 and trying the 6, the 7 wins out. If you only shoot iAuto or A then that's fine but if you shoot manual, like I do, the 7 is heads and tails better.

The 7's biggest advantages are manual controls and flexible files in post. If your shooting style requires none of those, then the 6 is the right one for you.