My system is set up with a mini itx HTPC (A10-5700K APU, 120gb Corsair Neutron, 4gb Gskill DDR3 1600 Eco (1.35v) ) and I stream all my media from my data dump in my office. The data dump has a Samsung 840 for Ubuntu and apps, 2x 4TB drives, 2x 2TB, and 1x 1.5TB.
The 4TB drives are both Hitachi HDS5C404 models and have had no issues at all. According to SMART one has been running for 1 year and 27 days, and the other for 10 months and 2 days. Neither have had any errors and manage to run around 24-30c in an Antec 300 with twin 1200 RPM 120mm fans blowing over all the drives. The drives had initially been running 24/7 for several months but I eventually configured the drives to put themselves to sleep individually after 10 minutes of idle. By sleeping idle drives I manage to save about 40-50w under typical usage. Paired with an Intel 2100T it has proven to be a very efficient and powerful system, I am quite happy with it.
I had some minor issues setting up and formatting the 4TB drives under the earlier versions of Ubuntu, but the latest kernels make things a breeze. There is one specific software whos name escapes me right now that made it a lot easier when adding that 2nd drive. But performance, reliability, efficiency, cooling, noise, etc have all been exceptional.
And $189 is quite a tempting price, I paid somewhere around $250-220 for each of my 4s - but as noted above that was a while ago.