kinda late to this thread, but here are a couple other links about drivers and "clarity." When I think of clarity, a lot has to do with low distortion, a lot with the proper alignment for the application. As Electrodynamic posted the link, this applies to the so called "acceleration factor" of the woofer. A paper titled Bl/Mms - Nonsense explains the flaw in this.
http://web.archive.org/web/20010810141852/lambdacoustics.com/library/whitepapers/bl_mms.htm
The "speed" of the woofer is directly equal to the frequency being played. The fastest woofers are the ones that can play the highest frequencies. This has nothing to do with size and actually nothing to do with mass. Our TD15M can play upwards of 4KHz on axis and sounds better at these frequencies than the 10" or 12" version. The reason in this case is due to the cone profile on the 15" driver. The reason all of these drivers can play so high is due to their extremely low inductance. The TD drivers may very well have the lowest non-linear distortion of any driver ever manufactured. Again, here is a brief overview of the Lambda motor, but it explains a lot about woofers and distortion in general.
http://www.aespeakers.com/Lambda001-1.php
John