I have been using my raspberry pi 3 as a server for yonks now and it has proved almost bullet proof! I genuinely do not you could get better bang for your buck!! I have a 4tb drive connected to it with about 95% of the content being mp4 which means almost everything is direct play or if not its just the audio being transcoded. Saying that I have transcoded other video formats on my home network which has proved fine. After a rather unscientific test I was able to stream 8 direct plays on my home network and two direct plays on my outside network working at 80%CPU which i think is amazing!
I think the vast majority of people who probably have a server for themselves and maybe a few friends and family this set up is very cheap and efficient. After all who wants their power hungry PC on 24/7!!
Anyhow I am always seeing the most complex instructions online explaining how to set up PMS on a raspberry Pi using rasbein etc etc. I tried and failed at this and found it far too complex not user friendly so here is my VERY simple set up..
install openmediavault on your SD card and install as you normally would...
install PMS as a plugin, mount your drives, set your permissions
away you go perfect...
Here's the video I used from Richard Smith which explains everything