I'm with you Nic, except I don't even use it to focus except in low light. In good light, I'm set to manual focus and then the WHOLE touch screen is just a shutter button and you can touch it pretty much anywhere (except the extreme edges) and it will fire the shot.
Ah, interesting strategy. I haven't yet used the touchscreen without autofocus, although I've being using the 25mm almost exclusively which has less DOF to play with and usually needs to be focused right. I imagine it would work well with the 9-18mm, as well as the 12 and 14.