I haven't used it in a good year or more. It was like the .04 release, before Plex 9 release.
In my experience, it worked on the PC front end client. I haven't tried it on the Roku. I did try it on the Android client. I could move around in the menus and setup. It just wouldn't play the TV stream. I presume that may not be any transcoding build into the plugin.
Not hat you haven't, but this is question well more suited in the plex forums, especially in the thread for the HDHomerun plugin.