I didnt get to finish typing my response earlier at work.
I'd recommend a Drobo for music over any NAS or server. Drobo is by no means the fastest, but chances are you simply don't need all the bells and whistles of the usually-more-expensive servers.
Lately my Drobo has been quite quiet, except for when waking up, where the drives initialize. But there have definitely been moments in the past where the fans were noticeable. For what its worth, they claim the Drobo 2.0 is much quieter than the first iteration. I can't confirm this, as I've only had the 2nd iteration.
Without a doubt my favorite part of Drobo is the ability to mix and match drive sizes/brands.
A kickass raid 1 setup isnt going to do me much good when I can no longer find a replacement for a specific make and model of drive, which will likely be obsolete by the time a replacement is needed.
This whole scenario is moot with Drobo, just buy whatever drives you goddamn please.
edit: I cant speak to video, havent tried it.