I have been experimenting with this myself ... so I only have my own experiences to go on.
I have a 2011 i5 Mini which I use as a media server. I recently (yesterday) replaced the internal 1TB and SSD drives with a pair of 2TB Samsung hard disks in RAID-0 for speed. This is the boot drive, and also holds about 500 movies, 10,000 songs, and many TV shows as a iTunes server. It also contains a photo library of photos I want to share, and "archive" files I want access to from any computer I am using. It also acts as a printer-server for guests on my network without the need for printer drivers.
I then have a 4TB hard disk in a OWC "MiniSTACK" for nightly CCC clone backup connected by FireWire 800. This is a pretty "static" system so I don't feel the need for Time Machine on the Server.
Since the Server is idle most of the time, I also use it as a Time Machine backup NAS for all the other household computers. For this, I am using a OWC ThunderBay IV with 4 ea. 3TB hard disks in RAID-5.
The Server is also connected to my TV in that room for video streamed from the internet such as missed TV shows. I manage it either from that TV, or via screen-sharing to whatever computer I am on.
This server configuration seems to be evolving, but I think I am close to my permanent solution for it.
Question for others here:
I think I have all the access permissions straightened out, but am still considering whether to simply have the Server under my login, or if it is better to have a separate Admin login for the Server (considering access to the iTunes store, App store, etc.).
Also, should the active Server login account be running normally with "administration" rights, or restricted rights for best security?