Do I Need an NAS?

I’ve been testing a few NAS appliances, and have been going back and forth as to if I actually need them on my network.

The NAS appliances have some nifty features such as web servers, MySQL servers, automatic BitTorrent downloaders, etc.  The features I actually USE are Network Recycle Bin and TwonkyMedia servers. 
Where I go back and forth is the speed and electricity usage of these appliances.  At the most, the QNAP TS-409 eats about 35 watts of power, and I can have up to 4 hard drives. 
The reliability of an NAS appliance is nice, but it certainly doesn’t replace a good backup strategy.  I’ve read on QNAP’s forums how some arrays fail when upgrading drive capacity (which can take up to 15 hours or longer to upgrade a RAID 5 array).
Another sore spot is these devices’ performance.  They use an ARM-based processor (similar to Pocket PCs), and the RAID arrays are completely software-based.  The QNAP seems to performs better than alot of other NAS appliances, but still has a horrible 7MB write speed, and 10MB/sec read speed… woefully inadequate for copying large files.  This is ok for media streaming, but what’s the point of the “automatic downloader” for copying large files if it takes forever to copy or extract them?
I could create DIY NAS from old hardware, but
a) I’d have to research the software I need
b) It wouldn’t be completely “appliance-like” (I’d have support it)
c) it would eat up 200W of electricity
It is nice to know what I always have an “always backed up” copy of my data on a device that sips electricity, but I have a Media Center computer that is always on, so why not use that as my NAS?  I could even add TwonkyMedia support to it so non-MS devices could access the media. 
If I can add a “network recycle bin” and automatic download application to the Media Center then there really is no reason to use an underpowered NAS appliance.
Alan is a web architect, stand-up comedian, and your friendly neighborhood Grammar Nazi. You can stalk him on the Interwebs via Google+, Facebook and follow his ass on Twitter @ocmodshop.