i honestly wouldn't want to shoot sports with a full frame body. the 1.3x isn't a big jump in focal length, but it most certainly is a boost. Only having a 300, I prefer all the extra length (yes, i know it's not really any longer) that I can get. Just my opinion...

it's frustrating shooting with a 35mm body and not having the extra reach that the 1d gives me. I'm pretty sure canon KNOWS that sports shooters like this feature, and most of us would be up in arms if canon ever switched the 1d line to a FF body.