What is your sport?
Several studies have shown positive effects of higher protein intake for strength athletes. I dont know anything about endurance athletes, but for honestys sake it has to be said that Dave Noisy has not produced any other evidence apart from anecdotal and some guru advice to back up his really low protein intake experiment.
So i guess it depends how adventurous you want to be
It probably makes such little difference for endurance athletes that even with negative effect you wouldnt really notice it, and could keep on progressing even if a slower rate, or with just long term negative impact and it would only matter if you were really serious about your sport.
Since this is in New Vegan section, it has to be said that protein intake level doesnt have anything to do with veganism. being vegan doesnt require low protein intake despite the reputation and there are many people who are vegan and eat a high protein diet.