Move from a Pen to a Nex?

I tried this question on the Nex forum but could not get a straight answer. I would really appreciate opinions from people in a similar position or those with experience of both cameras.

The decison I am trying to work out is fairly straight foward. My current camera is a Pen with the 20m Panasonic. With that lens I can focus in very low light (kit les virtually blind) and the colours are good (800 max iso) What I don't have is as much resolution as I would like. I often crop - pictures within pictures - and I like to print large. On a very personal note I also need image stabilisation.

What do I want? what I cant have, the image quality of an Eos Ids Mk111 or Phase medium format. Even if I could afford either I would not want to carry them.

Straight foward then! for me, would a Nex 7 (or a 5N) give me significantly improved reliable image quality over the Pen? Would I actually see that in crops and large prints?

Bill