My room is roughly 14' x 16.5' x 9.5 high. I have WP7 at the moment but am considering Maxx 2's. I just was emailing with Wilson today and they felt Maxx's would be "stellar" in my room so I do not think room size is an issue for you and neither does Wilson Audio.
In regards to the comment above about placement 5' off the backwall, I would strongly disagree. The way Wilson does/recommends setup, it is completely dependent on room. In my case, they fell only 1 ft from the backwall, aprox 2' from sidewall. This is not uncommon at all according to Wilson trained setup guys with many many years experience.