I've been running unRAID v6.0.1 since release (ran most/all beta's prior to v6 stable also) and it works great. It offers built in/native docker support and a very robust VM manager as well. I'm currently running a windows 8.1 VM as my living room HTPC and it works great. I've got an nVidia 550ti video card passed thru along with the associated audio and just have one HDMI cable from my server to my TV and it's been working great for months now.
I have SABnzbd, Sonarr, Deluge, CouchPotato, SickRage and OwnCloud running in their own dockers on this same system and it runs for months without issue. The only time I need to reboot is when I start mucking about trying to update or change or test things.
As far as the slow write speeds are concerned, I write everything to my cache drive, which then gets moved to the protected array via the mover script at about 6am. The cache writes plenty fast enough for my downloads, and nothing else I write is so speed critical to me that the speeds bother me at all.
I've just installed a second video card in the server to use for a second/bedroom HTPC and am trying to decide if I want another windows VM, a Linux VM or perhaps a MC docker (if one gets created).
I don't think Theater View is available in the Linux version, so I'm leaning towards another windows VM, but if a dockerized MC would allow me to use Theater View, that would probably be best for me.
I know little about creating dockers, and would be of little/no help in creating, but would be happy to test any such attempts on my server and provide feedback.
FWIW, I can and do happily recommend unRAID v6. If you're on the fence, do give it a try; I think you'll be impressed. Also,
dual parity is on the roadmap for unRAID, which will hopefully be released sometime this year.