Hi Alex,
I had eventually come around to the same conclusion as you, and have a full scart providing my 'backup' signal for my Telewest/Virgin V+ STB and the L&R analog connections providing 'backup' for my Apple TV.
Although my local dealer gladly helped me in developing the workaround, B&O never once volunteered information about the Beovision 7's inability to handle PCM during the 18 month period that I was trying to get to grips with the problem. It was always suggested that it was my digital source that was the cause of my woes. It was only when I had similar problems with my Apple TV, that I then tried a variety of other the digital sources and came to the conclusion that the TV was ignoring completely valid PCM signals. When I asked B&O the direct question "Does the BeoVision 7 accept PCM via the digital connections?" then, and only then did they advise that it didn't. I believe the ability to handle PCM is actually part of the Dolby Digital standard, and so would have expected more from B&O.
Did you have a similar experience?
Alan