I'm a person who daily drives a Dual clutch, flappy paddle gearbox, which means I only have 2 pedals. Go and Stop. I haven't driven manual since I was 16. I'm not experienced in it at all except for the basics. Because I only have 2 pedals, I use my right foot for go, and my left for stop. It makes sense. Now I'm stoked I got my G27, so I go in and play some GRID 2. Fun game. Not sim, but it is fun. Here's the problem. My left foot is on the clutch for when I shift, and my right foot is on the gas. When I need to use my brakes, I instinctively use my left foot, ending up hitting the clutch. This picture sums up my experience with 3 pedals so far.
Also, anyone with a G27, do you know how to make the brake pedal not so damn stiff? Seriously, it's the stiffest pedal ever.