i have both my 20D and my 1Ds MK2 set up like that . . . its all what you are comfortable with... if you are tracking something like a race car, football, or birds mentioned earlier, for me its easier to hold that * button to track focusing then to hold the shutter release half way down, . . . . i have been working like that for 8 years, back to my A2 and 1N film bodies...
cw
www.craigwaller.com