We are currently on 2.015, is 2.1 different?
according to smf wiki:
Automated Installation of mods on non-default themes
"Smart emulation" to automatically detect a mod's version and to automatically emulate this mod when it is installed
Improved attachment security
Improved attachment error handling
SCEditor (New WYSIWYG editor)
Drafts
Enhanced admin panel
IPv6 Support
Built in support for jQuery
Full SSL Support
Verification questions support for multiple answers and multiple languages
Deny access to boards
Moved topics placeholders can be set to auto expire/delete
Topic preview when hovering over subject on message index
Likes System
Mentions System
Alerts systems for Notifications, Likes, and Mentions
Topic notifications can be set to Not Following, No Alerts or Email, Receive Alerts and Receive Emails and Alerts
Personal Messages automatically saved in sent box
Default theme is responsive
Ical calendar event export support
Gravatar support
just installed one istance of smf 2.1rc3 on a low budget vps with a spare domain.. I'll try it in the next weeks, I'm already looking for a replacement for another web-community