Was a little bit apprehensive when reading reviews originally, and bought these two run a 2/4 monitor setup.
There is some fan noise through the unit as expected but it isn't disturbing at all in our setup. When the rack is in its usual location, you can barely make out the sound even in the quite hall.
We're not running it at full power, but it didn't break a sweat during our initial load testing. Air stayed cool the whole time.