After reading through all of your comments, i am going to add in my two cents.
I own most of the items you are discussing: 7D, 24-70, and 580EX
My wife is a wedding photographer and loves this combination of setup although her arms are usually very tired after a weekend of shooting (she weighs about 110 lbs). Her shooting partner just upgraded from a 50D to 5D mkII and would compare the images from her 17-55 2.8 to our 24-70 and would consistently complain about the image quality of her lens and camera setup. Here are a few things to keep in mind about what I have experienced with our equipment:
If you are worried about dust, the L lens and 7D body would be your best combo. We have had the camera for about 6 months with 10,000 actuations with no dust problems at all.
The 24-70 has a hood that is appropriate for all focal lengths but the drawback is that it is a very LARGE hood.
We did a bridal portrait (with me as the assistant) using a 430 and 580 combo. We were only using the infrared controls (no radio poppers) and the range for the flash was about 15ft. That was on the long side and I had to make sure the 430's infrared receiver was pointed at the camera or it would not fire more than about 5ft away. The in camera wireless control will probably be about the same if not slightly worse. Saying that, I would suggest going with the 580 if you can afford it and have not already bought the 430.
Another poster suggested going down to 1/30s or slower with IS but you need to remember that if you are shooting events with moving people, it doesn't matter how good your IS is if your subjects are moving.
We have also shot with the 10-22 that supposedly has L series glass but I was very disappointed with the image quality out of that lens compared to the 16-35 mkII we tried out.
Hope my information has helped you. Also, our local Best Buy had both the 7D and 5D you could try out. The guy let me take it into their theater room to see the high ISO performance (just something to check into if you are interested as our local photo store does not carry those cameras).