Some sources of information:

• Tech Ingredient's series on building transducer-based speakers (YouTube)
• Exciters & Tactile Transducers 101 (Parts Express)
• Surface Transducer specification sheets (DAEX30HESF-4)
• Speaker building forums & various threads discussing surface transducers (Rich Meinke's build post)

My research is limited to Dayton Audio's models, but they are the only "good" ones as far as I know.

The high efficiency variant seems to produce high volume and balanced frequency response - and it's the one I chose.