After gathering a lot of feedback, and doing a lot of thinking, I've decided to make some changes. I hope you'll like them. Here's what I'm considering: there will be two types of groups, Basic and Premium.
Basic groups will have the following features:
Listed or unlisted in group directory
Public or private archives
Open, restricted, or moderated groups
Full moderation tools
Full hashtag support
Mute threads and hashtags
Fully downloadable archives and member lists
1GB Attachment Storage
Premium groups will have the following upgrades:
10GB Attachment Storage
Directly Add Members
Basic groups will be free. Premium groups will be $10/month.
Please let me know what you think.