Tough call but hope you are thrilled with your choice. I too was deciding between a Bluthner VII and a Bechstein V (or its successor the B). Lingering preferences for the bell-like brightness of the Bechstein over the more muffled Bluthner "golden tone" and having small children who I wanted to be familiar with a typical piano action rather than the lighter though lovely Patent action won me over to the Bechstein but it was close. Having played unrestored, restored and rebuilt examples of both and having the luxury of being able to afford a rebuilt piano I decided that was what I really wanted.
My room is probably double the size of yours but due to two rooms knocked into one (typical UK Victorian terraced house). It has a wooden floor but my piano seems to be voiced on the delicate side and doesn't require the lid to be shut nor a rug under the piano. If either of those options doesn't work for you then the piano can be adjusted in various ways (a shop technician once demonstrated to me on a new grand piano the effect of raising all the hammers a mere 3mm closer to the strings, a ten minute job - I felt it gave much better sensitivity, tone control and was way lighter. Clearly the shop didn't agree otherwise they wouldn't have it set up like that to begin with!)
Best of all though, Bechsteins (and Bluthners for that matter) restore incredibly well. If at a future point you find yourself with several thousands of pounds spare and feel your piano is looking sounding or felling a little tired, you could do what the previous owner of my piano did and send it off (in his case to SAP in Poland, there are other firms that restore pianos too but SAP seem to be regarded as among the best...) where it was stripped down, everything either being cleaned up to as-new or replaced. What arrived back was almost indistinguishable from a brand new piano straight out the factory.
Incidentally purists would probably pick up a difference between rebuilt and restored pianos - restored seems to mean fixing things that are broken or out of adjustment and cost is variable. Rebuilding means pretty much taking apart and putting back to an "as new" condition - in my case ivory keyboard completely restored, new strings, newly guilded frame, new hammers, mirror smooth black polyester case etc. More expensive but probably more satisfying if the ultimate goal is to get a piano in "as-new showroom condition".