As I see it, there's a tradeoff relationship between "monitor-sized" and "does Rock well".
In order to have good bass, a small speaker has to trade off efficiency. That's not a problem; the problem comes when "rock the house" levels are demanded of that small, low-efficiency speaker. A small speaker's thermal and mechanical limits are likely to be reached well before "rock the house" levels are, and sound quality takes a hit at that point.
Often a floorstander takes up no more real estate than a monitor-type on a stand, and the extra internal volume allows the designer to do things he couldn't in the smaller box, often resulting in a speaker that works better for rock.
That being said, one of the better small speakers for rock was the Cliffhanger Bulldog. A three-way in a market segment dominated by two-ways, the addition of a midrange driver allowed use of a bass-optimized woofer that had more thermal power handling and mechanical excursion than similar-sized woofer which had to reach up an octave or two higher. Out of production, they show up for used from time to time.
http://www.soundstage.com/revequip/cliffhanger_bulldog_followup.htm
Duke
dealer/manufacturer
