We're currently employing OpenProject[1], a Chili/Redmine fork with extensive Agile/Scrum[2] functionality. Despite all valid points against Redmine being bloated, it provides many features often lacking elsewhere (Auth Providers such as LDAP / Single-Sign On, Plugins).
We're going to release a migration tool from Redmine to Taiga in the following weeks. Please keep an eye if you want to try Taiga with all your Redmine projects.