Hi, I've got two of these cards running within my Mythtv (mythdora 12.23) build at the moment, its been running fine for months now. (apart from if it warm reboots, one tuner of each card drops off so I have to do a hard power off and power on to get it back but thats no problem for a dedicated backend)
I also had the issue your talking about, What I had to do was use the dvbscan application and dump a list of channels to channels.conf. Then in mythtv instead of doing a scan just point to the channels.conf and it'll find your channels. http://www.mythtv.org/wiki/Dvbscan
Having said all that I have not tried this one LinuxMce as of yet Im current in the process of building a 0810 build 23388 with the same card. I will try and repeat what I did on Fedora and see if the cards work.