Re: Double pedal with a smooth surface?
I kinda know what he means about the posture thing. With long boards, the pedal board gives way under your foot more easily than it does with regular boards. With regular boards your foot rests closer to the hinge where there's more leverage. So keeping your balance or bracing yourself is a little different.
OP, I'll add that I think it's harder to use your slide technique with long boards. I personally don't like it and prefer short boards in that instance, but I think my mapex falcons are excellent pedals.
I agree with Dre25