Best answer by UKMedia
Your right, the Beam is designed for small to medium rooms and would probably struggle in a 9m by 5m room but as you already have one, I would suggest you try it first before buying a PlayBar/PlayBase.
We then get into a much more complicated discussion as this is driven by aesthetics, personal choice, and budget. I would recommend a 5:1 set-up with the Beam, Playbar, or PlayBase, using your 2 x Play:1's as surrounds. I don't think that from a sound quality perspective there is much difference between wall mounted of sat on the unit but you may want to consider the PlayBase for the later use.