FreeNAS seemed difficult
So I went with Open Media Vault. It's been rock solid for the last two years and I managed to buy the HP N54L and 4 x 2TB for the same price as any of these boxes empty. It took a bit of fiddling to be sure but was still worth it for the saving.
I would definitely advise any friends and relatives to get the COTS models here rather than rolling their own as I don't want to have to do tech support for them.