It is highly unlikely the drivers used in the Seaton can begin to match the world-class TC driver you are using. That being said, the Seaton sub will likely produce more output over 40-50Hz. Now, the ported cabinet I designed you will produce incredible output down to 15Hz easily. I don't believe the Seaton sub could begin to match the ported AXIS using the cabinet I designed, especially under 30-40Hz range.
But I am having to guess here - with lack of good measured data of the Seaton sub. But it makes no sense that the drivers would match the AXIS - it would raise cost substantially and minimize profit.
But I would never buy a Submersive. For that price, one can get two 15" LMS drivers (Seaton's drivers will not be any match - not close - but no driver is a match for LMS right now) from Sound Splinter, a pair of sealed cabinets and two EP2500s. Far more capable set up/performance for same money.
-Chris