Hi
I find 3 majors advantages to choose the beolab 7 instead of the beolab 7.4 as center speaker :
- when you don't want to use your subwoofer, you just have to select speaker 1 and you have stereo sound
speaker 2,3,4 and 5 options use always the subwoofer
- when your pair of front speakers become faulty, you still have a good stereo speaker left
- the bl 7.2 or 7.6 is more powerfull