You know, i guess i could as well say my point of view on the plastic vs. wood subject is in a slight bias nature, because i do some woodworking.
Now thinking about it though, my only real expierence with plastic boards are of the.......lets just say, 'non clean' persuasion.
Upon which the pink airborne 'algae like' bacteria was present, and in abundance! That tramatic event lead me to never own one, and to really care for my wood ones!
So i really know, only from what i have seen and read. However, and in retrospect, the plastic board had a microban label on it as well, so i guess if you don't take care of it, it's not going to much matter anyway!