Ive held a 70-200 2.8 is mk1 on a 5dc before and it wasnt too bad. im not a small guy by any means.
as for a lens to travel with, i dont think id get the 24-70, id like the extra reach from the 24-105, and the 24-205 and 6d is very doable for me to walk around.
i was mainly planning on using the 70-200 for paintball, some portraits, and parties and such where i dont have to be so close to the subject and i can catch them being more of themselves, but mainly paintball... so i think weather sealing would be kind of important also... <<< i just thought about this last part.
does the sigma even have weather sealing? the 70-200 f/4 has weather sealing right?