Actually the weight are pretty close, 52.3 oz vs 49.2 oz, 3 oz different is negligible.
I took a couple shots with both combo and show the result to my wife. She consistently says that the 5D2/24-105 results are better. She says something about more blurry background
I'll bring the 5D2/24-105 and the 270ex and leave the 35L at home.
Thank you everyone for your inputs.