The Plugin currently does not work for me in Plex 0.9.7.28.33 or later. However, it works ok with Plex Home Theater. PMS tries to transcode the stream, which does even result in transcoded segments, but for whatever reason these will not be delivered to the client. PHT just sends the stream to the remote client.
There is a small problem with Channel lists which include a "/" in the name. You cannot switch to these.
While it is nice to access the Box with PHT, it does not add much functionality to what is already possible with enigma2. But if plex would support transcoding the stream so that mobile clients are able to use it, then it would make sense. I already have a setup which uses VLC + QTSS to deliver similar, but having this inside plex would be great.