I don't have a horse in this race, since I host on Google (pairs nicely with Picasa) but I feel like all this would be a ton of work for the mods. If people don't have their own backups of their images I think it's reasonable to say they have to sift through the photos in one big pile and find the ones they need. Great opportunity to trim the fat!

#alwaysbackup

I've always found that it's better to have pics offsite anyway, so they show up full-size in threads without having to click through.