I'll be buying two to replace my 1D Mark IVs.
I certainly hope this camera lives up to the hype. Canon has been plagued by Auto Focus missteps in the past and this appears to be another "newly designed" AF system. "Newly designed" hasn't always worked out so well for Canon with the exception of the 7D, but it looks like this new system will even blow that out of the water if it works as promised. I love my 7D so I'm really looking to put this new camera to the test.
You had problems with the 1D IV system? I used to have a 1D III with some problems that later got fixed but with my 1D IV and 70-200L II I actually find it hard to miss.
No I've never had any problems with my 1D Mark IVs, I was referring to the notorious 1D Mark III AF problems that seriously damaged Canon's reputation among sports shooters. That was the point in which many changed to Nikon and why they have gained a lot of market share on Canon over the years. Canon used to completely dominate sports photography (and to a degree still do).