I just added quite a few sets back to my members area that were "lost" for awhile after a drive failure...it's crazy but I got some fanmail from members on it like it was brand new...one who had sent a fanmail about the same update 2 years ago and he didn't even remember it. Silly boy
I definitely think most paysites can use their older content, or spin some of it into a separate site to come "free with your membership", do your own members area plug-ins, etc.