If you are upgrading to 7D just because you want better quality image, then I will suggest you to stay with your XXD or XXXD. For example, 60D and 600D(and 550D) produces same image quality under same settings. But you may ask whats the selling point if there is no difference in IQ. 7D has some use in fast/action photography, rough weather and of course if you want yourself to look pro then 7D is good for that. Back to the point, higher FPS, more manual control (like ISO selection by 1/3 stop) is something that you can find in your XXD. If you don't need those features, 7D will be a waste of your money. 

And there is a saying which says to spend less with your body, but to spend more in better glasses. 

To conclude, I will suggest you to upgrade only to a full-frame like 5D mark II because that's a whole new world and it will bring a lot of potential to your current field of interest. Good luck.