I cycled my tank with live rock. Curious about the damsels though. What kind of fish are you ultimately gonna have? I've heard stories about folks trying to remove those territorial little buggers later on after new, more expensive fish are harrassed and stressed.
Might wanna thing about that before you get too far down the road. With more rock, the damsels are that much more elusive. Might consider the blue/green chromis isntead.
"Life may not be the party we hoped for but while we are here we might as well dance!"