Hello, welcome to the "what to do now" times in the home server world.
Many of us are right there with ya.
What I can say:
1) your servers (at least the one that is hardware upgraded) will run all of the OS'es mentioned.
2) all the OS'es will do automatic client backups.
3) not sure about Plex, never used it, my guess is it would run on all os'es, would need to check.
4) chromecast not sure about, have not used one.
5) Win 2012E and Win 2012E R2 both have the setup inside of them to backup the server OS to an internal drive or network share I believe.
6) when changing to a different OS it is very handy to have the Video Adapter so you can see what your doing.
I will be running whs V1 on my upgraded server with 9 clients as long as I can. I have a second server running the same OS that I use to synctoy the main server to about once a month, I also use non-pooled backup drives in the main server to backup the shares. I use serviio to DLNA stream my video to my Samsung plasma tv.
So my data is backed up like 4 times and streaming works fine for everybody on my giga network.
I built a DIY win2012E box (just in case) it has a win7pro VM running on it, but it is just for playing right now. I really hope I don't have to use it.
I believe there are trial versions on win2012E and R2 that you could try and if you liked it you could look for a good price. I have seen win2012E for around $300 R2 might be a bit higher.
I tried R2 and didn't like it. You would think they would be about the same, but for me the R2 give me more difficulty to get setup.
Hope this helps,
Some have gone win7 some have gone Win8 some have gone win10 but client backups become a problem then, (how to do them)
Let us know which way you go, as I said, others are in the same boat with ya.
Good Luck and enjoy
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