As an aside, I'd never handled a 300 f4 before but a couple months ago, I sold a 17-40 to a guy that was shooting a sports event (Final 4) and had a 24-70 and a 300 f4. After doing our transaction, I handled his camera with the 300 f4. I was pretty surprised at how light it felt. I think it's probably lighter than the 70-200 2.8. I have an old school 70-200 f4 non-IS and granted, his 300 was on something bigger than my 5D, a 1D, I think so maybe that made the 300 feel relatively small since the camera was so big, but the 300 was impressive manageable.