I have the 24-105 for my 6D and am pretty happy with it. I will be renting the new 24-70 in November for an event and letting a friend use the 105 on his 7D. A lot of the events I go to have less than adequate lighting, and even though my 6D is a low light monster, I'd prefer to keep the ISO to a minimum. I'll also be renting the 70-200 2.8. I have the f/4 non IS version, but it's not the greatest in low light. My only fear is that I'll like them both so much, I'll end up selling my organs to upgrade them.