Anyone have any experience with Ripole Subs?

"Unlike most other subs; the woofers in a Ripole are in an opposing push/push configuration. The resulting compression in the front chamber actually lowers the woofers' fundamental resonant frequency by as much as 10Hz (depending on chamber volume and opening area). Thus; the Peerless 12" SLS woofers, which normally have a resonance of 27Hz in free air, can potentially extend to 17Hz in a Ripol configuration."