Though I’ve never had the opportunity to use one for any extended period of time, I’ve been keeping an eye on Rob Galbraith’s on-going coverage of the EOS-1D Mark III autofocus issue. If you’re at all interested in very high-performance photographic equipment, the entire series is worth a read.
The most recent installment includes a video clip (about half-way down the page) of one of Rob’s test shoots with a sprinter. Damn, that thing is fast!