Transcoding with 8th and 9th generation Intel CPU's - will I notice any differences?

[Forced]

So I've been running Jellyfin in my Linux home lab for awhile now on an HP Prodesk with an i5-8500.
I also have at my disposal similar PC's with an i7-8700 and an i5-9500 respectively.

It occurred to me that I'm using the weakest of the three for Jellyfin, and the newest of the i5-9500 is simply our home daily browsing PC, and the tinkerer in me wants to switch it all around for optimum utilization.

Is there potentially any real benefit from upgrading to one of the two newer CPU's, either the i5-9500 or the i7-8700?
Or would switching things around be a waste of time 

[TheDreadPirate]

Besides the number of threads, which probably won't make a difference, there is no meaningful difference in the performance of those CPUs or their iGPUs.

The GPUs support the same codecs and will perform about the same when transcoding.