Hi ricvl
I hear that the Paradigm DSP 3200 may not be as strong a unit on the bottom end as many thought when they bought it. The Seismic 12 is a more formidable unit BUT with under 3000 cubic inches of external volumetric size it will NOT play Paradigm's boasted 17hz. This defies the Acoustic Law of the Resonance Frequency. Even with a 1500w amp and two passive radiatorsl the unit will not move that much air to go down to effective subsonic levels. Paradigm really inflates their numbers.
I own a DSP 3400 which I now will be putting up for sale and at 7300 cubic inch external volumetric size it will go down to it's lower cycles although not at the effective advertized 19hz.
For low bottom end, there is no replacement for displacement and you must add quality to that equation as well.
At the end of it all go for the Seismic 12. You will be happier.