I really tried to make the screen for moving focus points on the R, but being left eyed, I found my nose moved it more than my finger did. I tried limiting which area of the screen was active, but had no luck. I definitely prefer the joystick or the eye detect.
The one time I got to play with an R (for an hour or so), I certainly didn't have time to customize/debug it for my quirks, and my nose was constantly moving the AF point. I too am left-eye dominant, but can't imagine this wouldn't also be an issue for right-eyed people...the screen center lies to the left of the viewfinder; thus there's actually more space for your nose to hit the screen if it's to the left of the eye using the viewfinder.