So it seems the consensus is we should keep saving our pennies, until can afford the 70-200mm f/2.8L IS USM II.

The 70-200mm f/4L IS USM *should* work, as *should* the 70-300mm f/4-5.6L IS USM. It's a coin toss as to whether people prefer the constant f/4 vs. the longer reach.

The next question becomes, if the f/2.8 AF sensor slows down AF, is it actually going to reduce servo performance? The camera will have to work harder to lock onto a bouncing non-constant speed object. Will the increases sensitivity combined with the slower performance mean fewer focus locks, and therefore, fewer shots?

I'm glad there isn't a simple answer to all of this.