Thanks for the tip!
There are a couple of nights this week that there are only 1 or 2 new episodes of my shows coming on so I could set up both DVRs without having to worry about conflicts just to test it out. I have 6 tuners between my Duo and Quatro models so I will be fine with that.
My only other concern (which may have been fixed with the 6.3 Shield update) is that in the past when I tested using the Plex Server I had some issues with the External USB drive disconnecting randomly. I will make that part of my testing.
Thanks again, let’s see how this goes!