Other than the fan noise from the add-on mounting kit, no issues with the Sonnet Echo-Express III-R with 2 HDX cards (and a SAS card for the 4 SSD's) running PTHD 11.3.1 on OS 10.9.5 - late 2013 trashcan. Samsung 840 Pro and 850 Pro SSD's.
Just bought one of these to move the SSD's back out of the III-R. Obviously, if I had a machine room or a way to isolate the rack, this wouldn't be necessary. The noise isn't HORRIBLE but since I'm 3 feet away from the thing, it's loud enough to be annoying.
http://eshop.macsales.com/shop/Thund...nderBay-4-mini