Help with Plex server CPU decision

You spent a lot of time writing this extremely detailed post, and I commend you for that.

But I’m going to give a short reply, and I hope you don’t take offense to that.

Don’t combine everything you want into one box. It’s going to cost way more than it needs to.
Separate 2-3 machines out for dedicated uses:

  1. NAS
    Where all of your storage is located. The hardware requirements for a simple NAS are super low, like the NAS Killer 4.0.
  2. Plex (QuickSync)
    HP 290 or similar dedicated transcoding box, like the OTiS.
  3. BlueIris (QuickSync)
    Again, HP 290 or OTiS.

Even the lowest end recommended QS CPUs can handle 20+ transcodes or 6 1080p cameras.