I really want the new 24-70 for my event photography and for that same reason (2.
I wanted to upgrade the 70-200. I will test out the 24-105 before I sell it for the 24-70. I shoot families and kids and models, most of those I can do with the kit f4 lens and my 35L/85 1.8. When I do school plays, high school reunions, military events and eventually, weddings, I am thinking I will wish I had the 24-70 and 70-200 2.8's.
Right now, on my T4i, I use my 17-55 2.8 and 35L.
I could get this kit with 24-105 and when doing events, I guess I could use my T4i with the 17-55 with the primes on the 5d 3. That would save me a few expensive lenses.