Well the STF-2 is basically a one dimensional sub, ported. If you like it, fabulous, and I expect that you will. If you want to change it's sounds to fit your preferences, you have no real options. The VTF adds the ported or sealed options and the Q control. You can really tweak the sound of the sub for more output or to go lower with the ports open or closed and the Q control allows you to control the tightness of the bass. In your situtation, I think you probably went the right route and got the STF-2 to start and stay within your budget. If you can't tweak it by placement and audyssey settings to get to where you're happy, and then still feel like spending another $150, you have that option.