I am looking into upgrading as well. Here is what I was able to find. Plex wiki suggests a 2000 passmark score for one 1080p transcode and 4000 for one 4k transcode. However, if you convert your media for directy play then you can handle more streams at one time.
I mostly use handbrake and tunes kit to convert to a format that plays directly on apple devices with no transcoding and most of our family runs plex off of iOS devices and apple TV’s so we have been able to get away with a pretty wimpy server.
here is the link from Plex:
Here is the link to the scores for both of those processors. I think I selected the correct processors.
Passmark Scores new Mac mini 2018
The numbers would suggest you could have two 4k transcodes with the base model and three 4k transcodes with the $1,099 build. Or you could have four 1080p transcodes with the base model or 6 1080p transcodes with the $1,099. However, if you mainly use direct play with apple devices, you can handle a lot more streams at one time.
