I'm curious how truly valuable f/8 AF is. I have some friends who shoot a lot of air shows. Most of them use the 70-200 f/2.8 and/or 300 f/2.8 lenses, often with a 2x TC, which would put the aperture at f/5.6. All of them have numerous stories about the times they put on both a 2x and a 1.4x on their 300's, which would put aperture at f/8. All of them have also noted, on many occasions, how painfully, PAINFULLY slow AF is at f/8 on a 1D series body.
If AF at f/8 is really that bad...is it really all that important? How many people use and *need* f/8 AF to really make it worth Canon's while to "fix" the "lack" of it in the 1D X?