Looks like the concept of offsite backup is well talked about, but did want to add my additional thoughts in that it is very critical for anything important. I saw a number of disasters wipe businesses out when I was working at HP in the storage team. Some customers just sadly didn't see the importance, until after a major problem like a flooded datacenter. You have to get data far off site for it to be safe. I remember one story from a customer who had their business in the WTC towers, and their setup had their main datacenter in tower one and the backup in tower two. After the attacks, many businesses were moving the backups at least off the island. For home users, Carbonite and Mozy (among other solutions) provide that offsite backup without much setup or complexity. My personal solution is a Time Capsule at my grandparents house in Colorado. Every night, my old PowerPC Mini powers up, opens the Time Machine backup from the Mac Pro stored on my ReadyNAS, and uses rsync to send up the very important data of mine like all my photos. The initial backup did take a bit, but now that it's there, it's always completing the changes backup overnight.

As far as 4k drives and NASes, still check with your vendor. ReadyNAS Intel based systems added support for them officially with proper alignment in the recently released 4.2.12. Not sure if support for the 4k drives with proper alignment will make it into the Sparc (NV+ and a few others) based ReadyNAS units, but I do know there is at least one more firmware version planned for them.

Also wanted to chime in and say I've been pleased with the Samsung 2TB EcoGreen series. I have 3 of them running in my ReadyNAS Ultra 4, and have put them through quite a bit of testing during the beta period. They make a very weird spinup sound though. Performance seems to be around ~65 ish MB/s when attached via SATA. Not the speediest drives, but they weren't meant to be. I need to do some speed tests on them in the Ultra after a factory default, but from my earlier testing, I was getting native speed from them over the network too.