Rob Galbraith has conducted an analysis on the ground with the new firmware to see if the known problems autofocus were resolved after 3 firmware updates and a correction hardware. The problems are probably due to the new sensor for the autofocus mounted on these reflex and problems with a mirror mounted on some copies. During the start of 2008 in Canon has worked hard to correct the problem, probably with a view to the Olympics, since the problem manifested more in shooting sports performance.
With the new firmware the ability to maintain a subject static or moving to fire becomes very very high, but in some cases the camera still overestimates the speed of movement of the person. The situations in which the quarry better if people are moving slowly or moving gradually, like a runner crossing the frame.