I think that most people buy subwoofers largely by the numbers, and the numbers aren't kind to transient response optimizing designs.
Consider two subwoofers, identical in size and price. The first one is -3 dB anechoic at 40 Hz, and second one is -3 dB anechoic at 20 Hz. Which one do you think most people are going to buy?
What the numbers don't tell you is that the 40 Hz subwoofer has much better transient response than the 20 Hz one. Good transient response is expensive in terms of box size and bass extension.
I'm involved in the development of a subwoofer designed specifically to work well with Maggies, and if the project is a success it will probably be marketed through Audiogon. The design will be optimized for transient response, rather than for loudest deepest possible bass in smallest possible box.
I do not think that the surround itself is a dominant factor in the sound of a subwoofer. Rather, those subwoofers you see with the donut-like surrounds are typically optimized for loudest deepest possible bass in smallest possible box, and transient response is the casualty. The prosound 15" woofer mentioned by Jtgofish has parameters more conducive to good transient response, assuming adequate box size.
Duke