I'm running LMCE 7.10RC2 under the AMD64 version. I have some quirks but I don't know if they are related to that. My USB-UIRTs work fine, but I had to use Jon Decker's fixes to prevent it from sending the numbers 4 times each.
My two main stations, running AMD64, (basement core, living-room md), are working quite well.
I guess my biggest issue with other MD's is they won't load and run MythTV.... no matter what type of MD I set up (i386 or AMD64) MythTV loads to the menu, then exits about 30-60 seconds later. All other functions seem to be fine, and if I go to the KDE Desktop, I can manually load MythFrontend and it works OK from there.
Given that, the station in the master-bedroom runs MythBuntu and I sold off the machine I was playing with the office and am back to using the D-Link DSM 320 on the CRT TV, or I fire up my Dell Notebook and use it as a MD on my desk. I can watch our recorded TV shows with either machine but it means no commercial skipping unless I run MythFrontend from the KDE desktop on my notebook.
One other thing I've noticed is the alphabetical letters on the media screens no longer act as jump points. I could bring up the list of Videos before and click on "T" on the right and it would jump to the movies beginning with "T" but now it just goes back to page 1 no matter what letter I click on. I think this does work correctly when viewing Music, but not with Movies.
Another small PITA is the Media Sub-Type drop-down. When I add a movie I set this to "Movie" but if I move the file later, the media sub-type field resets to nothing, so I always have to make a note of where I moved things and then use Media Files Sync to set it back. I can resynchronize the directory too, but that doesn't make the media sub-type drop-down stick.
In the case of torrent files, LMCE can see the files that I'm downloading, but for me that is only their holding area. When the download is completed the files are moved into the various LMCE media directory structure dirs. Now here's another weird thing. I rename the file after I've copied it so you don't have all that other crap in the filename... I go add attributes to the permanent file, and when I delete the torrent file after a few days, if the filenames are close it will wipe out the media sub-type field!
So if I have "The_Exorcist.avi" in my permanent file area, but I delete the torrent "the.exorcist.1985.some.dudes.name.avi" I can be almost 99% certain I have to go back and edit the attributes on "The_Exorcist.avi". Very strange.
I may not be understanding how the media sub-type field is supposed to work... I spent about an hour tagging all my small music videos as music only to come back the next day and find LMCE set them all back to nothing. I thought attributes were supposed to make managing your media collection easier? If I set an attribute, why would LMCE then come back and erase my settings? Not very helpful.
I was thinking of doing a clean install on the next release and using the i386 version throughout, just to see if some of these quirks disappear.