I really think ’speed’ is not a property of the subwoofer driver, but of the room acoustics. If you look at waterfall graphs of low frequency output, you can see that the lingering of some low fequencies is at room modes. Deal with those, and your ’slow’ subwoofer suddenly becomes ’fast’ (been there, done it). I suspect that part of the explanation for the observation that big woofers are slower may therefore be that they potentially generate more room modes.
As for subwoofer design, I guess that everything else being equal sealed enclosures are more beneficial for music than vented ones, with designs with passive radiators somewhere in between. Vented ones are often preferred for HT and massive explosions (if that kind of movies is what thrills you) because they can go deeper and louder. SVS offer both designs. The Audioholics forum has many detailed discussions and measurement data.
As for subwoofer design, I guess that everything else being equal sealed enclosures are more beneficial for music than vented ones, with designs with passive radiators somewhere in between. Vented ones are often preferred for HT and massive explosions (if that kind of movies is what thrills you) because they can go deeper and louder. SVS offer both designs. The Audioholics forum has many detailed discussions and measurement data.