Right Foot here with a G25.
I prefer H shift and clutch, but before the G25 I had a DFP (which I still think i prefer to the G25), and with only two pedals, still rfb. I used to left foot when I drove GPL for the first two years (with a RSforce and then with a GPL Shifter), but I was a much better braker when I switched to Right Foot. I actually got quicker and was much tougher in the braking zone, and just felt like I had more control.
I think my brain cannot work both legs at once. And as I have trained the right leg in the real car to go and stop, I seem better with it like that in the virtual one.
Hippo