Hi Dave,
Looks like your room is about the same as mine: 14.5 x 21 x 9. How do you feel the Vantages perform within these dimensions? The Summits seem to shine in mid-size to larger rooms like this.
they perform superbly !!! Whereas my room is a couple of inches wider and two feet longer you have the advatage of an additional foot of height. No doubt Summitt's would sing quite nicely in your size room !!