My room is 15x20 but is also open to a kitchen area and stairs down to the first floor. Basically I wanted to see what kind of performance differences there is and if with the open area if I should go with the better sub.
The STF-2 goes lower, to frequencies suited to action DVDs, where the STF-1 falls a little short. Plus your room is very large. I have a STF-3 in a similar space.