Koputai, I have owned a 7D and shot it side by side with 5dmk2 for weddings , landscapes, stars (and now comparing to the mk3)
I would not offer a print for canvas for a client shot at 1600 iso in dark reception light with the 7D.
The 7D on the other hand performs incredibly well for its sensor size for landscapes with the 10-20sigma -BUT, I wouldn't even think of shooting stars with it apart from possibly star trails. (for instance, our sales for landscape prints before we got the 5dmk3 were split fairly evenly between 7D and 5dmk2 shots)

Perhaps I wasn't being clear - I'm only talking about high iso performance referring to the full frame models , not general performance- it's true that it's high iso performance is better than the previous aPS-C models but having upgraded from the 40D, I was disappointed at how marginal those particular benefits were. Perhaps I'm a pixel peeper and paranoid , but I stand by my comment that I would not offer high iso prints /sales at any size above 12X8" unless I intentionally wanted a grainy look. Hence the comment about displaying on web and sharing images. You're welcome to disagree but this is my experience I wanted to share with the OP.