I have the HSU VTF3 in an 11' x 17' room. It is in a near field placement right behind the sofa. It is only turned up 1/8 of the way for music use and just a little more for movies. It is more than enough for my small area!
The first thing I did before my sub purchase was to email my room set up to HSU and got a reply from DR. HSU himself within a short period of time. His suggestions for my room were dead on. The sub intergrates with the rest of the system and is one awesome piece of equipment. I vote for the VTF3 but give a email to HSU and see what they say.
My current illness includes the following symptoms:
TV: Sony 50” SXRD
Receiver: Marantz SR7500
DVD: Marantz DV7600
CD Changer: Marantz CC4300
Power: APC H15
Speakers: (JBL) Soon to change to Ascend
Sub: HSU VTF-3 MK2