For me it has two uses. In studio it's useful and the bug doesn't bother me, I shoot at a regular 1/200 f8 iso 100. I had got excited about it for street shooting. Setting the camera to RAW but the jpg's to B&W for the preview plus other custom features, and setting that up for a street shooting rig, without having to go through the menu's changing everything when I go to work that night would have been extremely useful. If however the fstop or ISO set in 'C' mode resets everytime the camera comes out of sleep, and leaving the camera fully on for hours at a time is utterly impractible, the C mode becomes far less attractive.
At the time though if I dared to mention this online I was vilified for not being happy that I had the C mode period and to quit whining, to buy a couple more batteries (the canon one's cost a heck of a lot), etc. No doubt some people will be saying that the AI Servo problem is just with certain lenses, so don't use them and stop complaining!
Because of course one should except such issues with a camera costing over $3000....
