The Mahler's would over power your room, IMHO. I think the Strauss may too. If interested in the VA line your room may be best suited for the Beethoven Grands. I've had Beethovens, and the Strauss in my 15 X 25 room, and thought the Strauss was pushing it in my room. The VA's are rear ported designs that need to be brought well out into the room in order to smooth out the bass properly. They can sound boomy if too close to the wall or with too small of a room. The Beethoven's sounded very good in my room. The Strauss sounded a bit better on top, but the bass was fuller, but not as tight.
The Mahler's were too much speaker for my room. Since your room is smaller, I would think the Beethoven Concert Grand's would be the best choice for your room in the VA line.
If looking into the Sonus Faber line, check out the Cremona or the Guarneri Momento Homage.
Enjoy,
John