You could also consider Thecus N7700 series.
Refer to http://www.thecus.com/product.php?PROD_ID=14
It basically seems to be Freenas with a reasonable management GUI in a 7 slot box with support for both Apple and PC and iSCSI et al..
Supports RAID 5 and 6 and now has a 10GE interface.
I run a 7x2TB and a 7x3 TB setup which yields 8TB and 12 TB formatted data space. I prefer RAID 6 as it can take more than 12 hours to rebuild a failed array. This puts a RAID 5 setup at risk during the rebuild window.
The Thecus does only have 1 power supply, so there is no redundancy and hence a single point of failure, but it has been good enough for SOHO use. In three years I have not had any failures except for drives.
I prefer normal Seagate drives, not the more expensive Enterprise quality, they last between 14000 and 18000 hours, that is between 1.5 and 2 years, and the price is OK. In my setup WD has had recurring failures in the first 1000 hours.
Swopping drives are easy. The system is hot pluggable so you simply unplug the drive carrier, loosen the four screws that hold the failed drive, replace drive, refasten and plug back. The system detects the new drive and functions in Degraded mode until fully rebuilt. No real impact on user experience.