Having tried a few different speakers of different efficiencies in my rig over the last few days, I don't believe speaker efficiency has a direct correlation with perceived dynamics.
The two pairs of monitors I tried are a few dB more efficient than my reference towers and they appeared to lack in dynamics, I believe the lack of LF extension is directly responsible for this, although driver size could also be a factor. The towers are tuned to 20hz, meanwhile the monitors are tuned to 40hz and 55hz. The speakers contained a 10" woofer, 2 6.5" woofers, and a 5.25" woofer respectively.
The two pairs of monitors I tried are a few dB more efficient than my reference towers and they appeared to lack in dynamics, I believe the lack of LF extension is directly responsible for this, although driver size could also be a factor. The towers are tuned to 20hz, meanwhile the monitors are tuned to 40hz and 55hz. The speakers contained a 10" woofer, 2 6.5" woofers, and a 5.25" woofer respectively.