The 24-105L is a fantastic lens. I can't wait to get it....again! Sold mine years ago. Loved it but on a crop it was replaced by my 17-55 IS 2.8. So I have that on my 60D and the 24-105L will be perfect on the 6D.
I was shooting today with my trusty 24-105 on the 6D and I was amazed at how wide it is after using it all these years on my crop bodies. Like having a new lens in the bag.