Hi Ofseng,
I would not call your room size "small" per se.
I haven't heard the Vantage in a room I trust but am very familiar with the Summit.
Factors that impact room "overload" are:
1) Excessive / loud volume levels.
2) Playing material that is excessively bright or has significant amounts of mid / low bass content.
3) Speaker placement that augments "beaming" and standing waves.
4) And probably the most important, lack of acoustic treatment. If properly installed, acoustic treatment that diminishes reflectivity and absorbs excessive mid / lower bass energy will significantly attenuate or eliminate room "ringing' or excitement of bass nodes.
I'm confident that if you address the four items above, you should not have an issue with the Summits. Also, the Summit allows for more control of the mid / low bass output as a result of having two adjustments (25 and 50hz controls). The Vantage has no such adjustment. And the Summit has powered woofers, which will allow your amp to only drive the panels. Less strain on your amp means more headroom, cleaner / more transparent sound thereby decreasing overall distortion.
From my perspective, this is a no brainer.
Good luck.
GG