Slack kills me. A group of friends of mine from college use it to stayb in touch. Our instance has a dozen or so users, half of them mostly lurk to stay in the loop. For us active members it would definitely be worth paying 7.25/mo or whatever it is, but we don't want to lock out the others who don't really use it so often and they definitely wouldn't pay for it (and some can't really afford it).

I wish they had a tier below Pro for personal use (we aren't a business) that gave full post history and limited everything else and was maybe not per user billing but instead usage based. It's such a great, intuitive platform and works perfectly for our group of friends except that you can't go back to look at anything.