I switched last month to straw from pine shavings because I found the shavings fairly quickly got pulverized and then ceased to be a nice cushion (for walking around and as a "landing pad" for when they fly off the roost). This created two issues however: one, they soon preferred to do their laying in the straw versus the nest boxes; two, the elevated pile gets in the way of the main and chicken doors. Neither one is a big deal, as I planned to elevate my doors at some point anyway-and who cares where they lay as long as they lay? My major concern now that I think about it is that the straw seems a place where moisture could be trapped and not be immediately apparent and as everyone knows, moisture is THE enemy in a coop but so far, so good; I plan to stick with straw but to change the bedding as often as I had been changing the shavings (once a month-ish).