ESRF (European Synchrotron Radiation Facility), Grenoble, France
ESRF migrated from Centos 5 to Debian 6 in 2012, starting with the control room's workstation, data analysis workstations and clusters. For data analysis Debian offers both the richest environment including the most used software and libraries in our field of research, and a rock solid distribution with security fixes.
We migrated again in the summer of 2014 to Debian 7. We look forward to our next challenge of making GPFS work on Debian.