Here are my thoughts on the CP5700 (I own one).
You may have trouble taking photos of fast moving objects due to the fact that AF
is a little slow, but not too bad. I don't recommend it if your main purpose is taking photos of the Blue Angels and the like (or maybe I just need more practice). I currently have 20 photos on a.net, and all but my oldest 2 pics were taken with my CP5700. However, the quality of those CP5700 photos may not be the highest, as I have taken all of them through windows (airplane or airport windows). I have needed to adjust levels, etc in photoshop to make the photos have no tint, etc. I take all of my photos (so far) in Normal or Hi jpeg modes, so they may not be as good as RAW, TIFF, etc.
My CP5700 has worked fine for me, as I am usually taking photos of planes on the ground, or window views from planes. I hope this helped.
btw, when u came into London on May 11, I was leaving that afternoon from LHR