Wow just read through this whole thread. Some good information mixed in here and there. I just wanted to add to the anticipation vs. FPS discussion. I have to agree with those who have stated it takes a little bit of both sometimes.
I've been trying to get a shot similar to this one here for about 6 years now. Although I've come very close I've never quite gotten it. The reason being is that with a closure rate of well over 500 nautical miles per hour you have to anticipate the crossing to start pressing the shutter button, but to get the exact alignment of the two planes you need a high-FPS. Human reaction times are just not fast enough to solely rely on anticipation.
For some photos, I'm sure this is true for sports photos as well, a 1/100th of a second difference can have a huge impact on the shot's composition.
this is an interesting photo.
anticipation vs FPS. First shot vs follow up shots.
if you had a 1dx, your shots would be spaced out 71 milliseconds apart (0.71/100th or 72/1000th).
7D 125/1000th of a second apart
6D 222/1000th of a second apart
so to maximize your chances, a 1D3/1D4/1Dx would be the way to go.
might be easier to use photophop to layer the image perfectly