While I hadn't heard of that particular NAS package, I was more looking for advice on good hardware.
Originally, I had thought to just use my tower and whatever software, but, as I said, I learned that hot swap trays aren't available for my tower, and, indeed, it seems to be recommended to get a dedicated storage unit (not rackmount, though, for my use case).
My needs are at least 6TB of usable storage. With that much storage, I wanted to have some amount of assurance of data integrity and safety (though I realise that a single raid system isn't a replacement for backups), so I'm looking at RAID 10. RAID 10 seems to be a nice balance of speed and safety (though, frankly, speed isn't a big concern), and it lets me reduce the risk of multidisk failures (b/c there is no parity needed to recalculate) when a disk does die.
The reason why I want hot swap (even if there is a hot spare), is b/c I want to reduce the probability of near simultaneous disk failure leading to array destruction.
For the RAID support, I've been a bit indecisive between mdraid, a zfs solution, or a high end raid card. Again, the thing I care more about is not losing the data.
ZFS has a mature data scrubber (which is important, b/c I've noticed that I get a seemingly large number of file corruptions on infrequently used files), some of the raid cards provide a version of this feature, but I've heard that it isn't as reliable, and if a raid card dies, you can have problems recovering the array. A problem with ZFS, however, is that it doesn't seem to offer a raid 10 like solution, so I'd end up with the array rebuild problems caused by parity.