Just caught up to this thread....

The STF-3 is actually tuned closer to 22Hz. In 25Hz tune, the VTF-2MKII and STF-2 are virtually identical. The STF-1 has virtually the same capabilities above 32Hz as the STF-2.

Here is some real cool news:
http://www.lyrtech.com/investors/details.php?pkiddocument=191&types=N