Personally I think the 5D + 24-105 would be a great combo if the 24-105 was great.
My post is number 15.
I think my 24-105 is for sale. I have no doubt that of all my lenses (17-55, 70-200, TSE24 ii, 100 macro, and 24-105) it is the least sharp.
Shooting an oil painting from a tripod with all the precautions, my 30D + 17-55 easily outperformed the 5DII + 24-105. It was embarrassing for the 24-105.