Whenever Plex need to transcode media it requers a lot of CPU, so when multiple users watch movies , the media that will not play as direct play or direct stream limits the numbers of simultaneous streams.
When steaming to Chromecast, different TV apps, Ipad, and android platforms, mp4(x264) with acc (or mkv) always seems to play as direct play or direct stream (only sounds needs transcoding)
A lot of people use a NAS server to host Plex server, with limited CPU power, so It would be nice with a media analyzer, that tells you what media needs re-encoding for optimal playback. with an option to convert excising media so it can be played as direct play on your clients in the house.
Re-encoding media manually would take a long time when you have a lot of media. Often the NAS does not work in night, so being able to use it during off-peak to re-encode your media would be perfect.
Also when and if x265 is going to be the new standard, optimizing you media to this would save space and improve performance in regards to bandwidth.