Apologies, I misread the question and thought you were asking about the Sigma for your current camera.

Anyway, the Sigma is a very good lens indeed - as I say, mine is an older version (the first version of the EX lens), but that is pretty close to the Canon lens in performance terms. It's not as sharp at f2.8, though, which might be an issue for you. At f4, you would be hard pushed to tell the difference. The Canon lens also has IS, which might be an advantage, although it doesn't freeze subject movement, so for your requirements, not that big an advantage. For me, the Sigma is ideal, as f2.8 is not required all the time, but for you, that extra sharpness may be worth paying the difference for.