I want to purchase the Canon 6d. I currently own a T3i and I want to keep it as a secondary camera. I have the following lenses; the kit lens that came with the T3 (I never use), a Canon 50mm f/1.4, a Sigma 17-50mm f/2.8 and a Sigma 70-200mm f/2.8. I don’t think the 17-50mm is compatible with the 6d, but do you think I can get by with the 50mm and 70-200mm? Instead of buying the 6d with the 24-105mm f/4L, would it make better since to buy the body only and later buy the Tamron 24-70 with VC? What would you do?