I've got one of the older Tunze skimmer models (240/1) on my 165 gallon system. It's essentially a bigger version of the current 9210 model.
http://www.jlaquatics.com/phpstore/s...t_ID=tz-ps9210
It is quiet for a skimmer. Quieter than my old Euroreef CS6-2 with a Sedra meshmodded needlewheel and skims as well as the ER.
Tunze takes an entirely different approach to skimmers than what most people are used to seeing - small and efficient. The Tunze probably takes up less than half the room of the ER and uses less electricity. It's probably not the skimmer for someone who wants to skim the beejesus out of their system, but it is a quiet and efficient little skimmer that gets the job done.
Tunze has a newer line of skimmers (9010, 9015, 9020) as well.