Some had complained about the noise of the fan, but in my situation, with two computers with several fans running, even with the Mediasonic fan manually set on high, it was barely noticeable.  I should point out that the computers have 5 fans each running, and even though they are "quiet" fans, just having 10 of them running at once makes a noticeable sound.

I now have the enclosure populated with all Western Digital drives, as I have found Seagate to be less reliable in potentially warm situations.  Three of the drives were taken from WD My Book USB 3 enclosures, while the fourth is a WD Data Center 6GB.  I do have the fan manually set for high, and the door closed, but the temperatures average around 90.  Naturally during backups and copies the temps do increase, but the highest I've seen is about 112.  After three months, no problems with the enclosure or drives.

Overall I'm pleased with the device.