Interested in how much content you have on those drives. Are you storing full bluray backups (40-100gb each), or are you doing like 10-15gb movies or the 2-6gb versions?
Right now one of the biggest things on disk are a bunch of Boston Legal episodes. I have family that enjoy it, and I'm too lazy to find a good small release so it's taking up more space than it needs to.
I try to get HEVC encoded video where possible, and when I know there's a particular release group that produces high-quality I'll set up tags to prefer them.