I have an older mythtv 0.25.3 backend but a new ASUS Chromebox that I want to use as a frontend, running Fedora 20. I decided to leverage Docker to establish a repeatable build process for the mythtv src rpm available from atrpms.
The 0.25.3-294.1 image is a combination of atpms EL6 and f20 rpms, plus several rebuilt rpms (ffmpeg, transcode, mythtv, mplayer) from src. It's currently deployed on a Chromebox running base install of Fedora 20 w/ Gnome 3. So far so good. I may try to backport a few fixes for some of the more serious bugs that have been discovered, but maintaining an EOL branch is not the end goal.
Future plans include testing newer builds of mythtv in Docker containers before I upgrade both my backend and frontend systems.