When you become a WPMU DEV member you get access to our awesome support and unlimited autoupdates.
Our members find our membership insanely valuable because of our support, with a full time staff of 15+ who actually respond to EVERY request, and work hard to resolve EVERY ticket. Trust me, you can't find this anywhere else.
And yes we do honor the guarantee if they've allowed us to work with them to resolve their issues and it's still not working out.