So I finally decided to upgrade my camera. I have a 1dmk3 (that I am keeping) and 6D that will help fund my next purchase. I pretty much just have my canons for portaits with my 85mm, kinda close wild life or zoo pictures with my 300/4 IS, and I can also borrow a 400DO or 500L from my friend which is awesome. I am not very sure about which has better AF for tracking and such, so what are your experiences with these two? I like the 1D style body but it seems the 1dmk4 is getting pretty old now. For now I am obsessed with humming birds and I usually hang out at the local lagoon taking BIF pictures.