Well decided on the Define C. Look like exactly what I am after, small, efficient and hopefully quiet.
My Haf X has most of the fans stripped out and the remainder running at next to nothing RPM. There is little airflow in the case but I have the top dust filters off and the CPU fan pointing upwards so all heat just goes naturally out the top. GPU is the only thing that creates noise. Hopefully the Define C will make that a bit quieter.