live rock is the way to go, at the shop i work for i always recommend live rock. i don't use damsels for a few reasons, 1 they almost always get mean as hell, especially dominos, 2even as mean as they are, they don't deserve to be subjected to the harsh cycle enviroment. 3 it takes twice as long to cycle a tank with damsels as opposed to rock. 4 the rock is comething you will probably keep in the tank, the damsels however, will probably have to be taken out because of their direct link to satan.