Sensitivity is rated as output in dB (with 2.83V input at one meter distance). FYI Klipsch fudges sensitivity a bit, likely its actually a few dB below that, but still a relatively high sensitivity for a speaker. Wattage ratings aren't very useful for much, more about their melting point and not that the speaker will actually sound good at those input levels.
Generally a larger mid-bass and/or bass driver is a good thing. Whether one speaker sounds better over another is about more than driver size, though, more in the realm of personal preference.