I have been using the 50D to capture my daughter's sports (soccer, hockey, volleyball, basketball) for the past year and have been very disappointed with the results, especially as it relates to focus tracking. I came really close to moving to Nikon (D300/D700) but quickly nixed this idea as I have a fair amount of Canon glass, some of which I use on my 5D MkII. So the question is, what can I upgrade to?? I have started to look at the 1D MkIII (used) or the new 7D. Just a note: weather proofing, professional feel and durability are NOT factors for me, I am looking for the best camera with 8+ fps, that will quickly lock on to a moving target and in a 10-15 shot burst, have the highest percentage of in-focus shots. I will be using the camera primarily with 70-200f2.8, but also with 300f4,135f2 and 85f1.8. A suggestion to wait for the 1D MkIV will not be helpful, as it will probably be out of my price range when it is released.