On a fresh 1204 DVD install, my tuners are correctly detected and corresponding devices created in LMCE. In MythTV setup, I can do a channel scan and the expected channels are detected, so communication with tuner appears to be working.
In MythTV setup under "Input Connections" the tuners are not assigned a video source by default. I can manually map this connection, exit the setup, reload router, but the setting does not persist.
Trying to watch live TV, I'm given the error that no tuners are available.
This exact same hardware setup works normally under 1004.
I created a ticket here:
http://svn.linuxmce.org/trac/ticket/2192#ticket