Razlaw, you are correct. I've been enjoying 7.1 LPCM on my BeoSystem 3 using all 7 speakers. After a lot of research, I've found that the issue with the BeoSystem 3 not playing the rear speakers in a 7 speaker setup with 5.1 LPCM blu-rays is an issue with "matrixing." The BS3 is not able to matrix 5.1 LPCM sound to use all 7 speakers. However, the BS3 CAN matrix 5.1 Dolby Digital into 7 speakers. As Geoff said, it can be a matter of personal taste. Some purists would prefer listening to a blu-ray movie with the soundtrack as it was intended. I, however, like having the added sound from the rear speakers. It would be nice to have this option.
I really wish that B&O would correct the menu so that it correctly shows 7.1 LPCM when that is, indeed the signal being sent and played. It's rather confusing to see 5.1 as the output on the menu when you know that it's 7.1.
Once you have the extra 2 speakers added to your setup, I could suggest some movies for you to listen to for taking advantage of those extra speakers. The first two Harry Potter movies in the Ultimate Edition (the big boxes - not the original small cases) are 6.1. Also, the Lord of the Rings trilogy is in 6.1. All of the original generation of Star Trek films are 7.1 (however, the New Generation movies are not). Sleeping Beauty is delightful in 7.1 Enjoy!