Would I notice the difference between a Canon 5D and a 1D MKIII when shooting fast outdoor sports like Motorcross? Is there a significant difference in quality of the picture? Should I even get a full frame sensore camera? Glass dosnt matter as I shoot pentax now. My only complaint that I know about is I want faster write speeds, or a bigger buffer. I am not a Spray and pray shooter looking for movie like fps. Everyone is going to say, "which ever feels best," or "a profesional would just know." But please remember, I have never used a full frame camera. I have read the specs. But just don't know if it would make a difference in sports photgraphy. Feed back from a sports photographer who uses either of these cameras would probably be great. If you think I am looking at entirly the wrong camera, then let me know about you profesional sports rig. Thanks everyone for your opinions.