I have already done the test. Zooming and moving around in the image to see the various areas of IQ is much faster via touch than using the joystick to move around on the image. The touch interface is instant, with no delays as you press and hold on the joystick, etc. There simply isn't any debate. I have run 1D series next to the SL1, and the SL1 was a joy compared to the old way of pressing the buttons, rolling the dial and using the joystick. If it wasn't, our tablets and phones would have alot more buttons and alot less touch.
Menus were also faster, you just clicked the menu header for the menus you want, there was no need to hit the menu button, select button, roll a dial, roll the shutter dial, etc. The Canon full implementation is very, very good.
Those that are poo-pooing the concept sound just like those that didn't like AF when it came out, or live view, or MFA, or video mode. Let's just say that these things don't appeal to you, but it doesn't make it any less valuable to others. It's okay if you are used to a certain function or feature, and don't want it to change.