The trouble with wood chips is that it's hard on the chicken's feet. Bumble foot. Another thing, the water wicks easier with the wood, and it gets moldy, mildewed, fungus, etc.
Did you have personal experience with this happening?
I use a lot of wood chips in my deep litter mixture and haven't had any problems. My run is covered, but gets some run off water into it, if it rains enough. Our son's deep litter is mainly wood chips in an open run and he has not had any problems. Both of these set ups produce some good quality soil.