Hello, we at the Firebird (RDBMS) project have a special license for being an open source project.
We use the tracker to derive reports and guides for new features, including a "What's new" that's part of the documentation.
One thing we miss from time to time is to be able to have more than one assignee to a feature request (less commonly is the need to assign several people to a bug). Things are complex and/or big there and sometimes one person is not enough, but for giving due credits to anyone is easier if we track all assignees officially instead of putting one person as the official assignee and having to remember later who else worked on the same issue.
Thanks.