Hi,
I have the HSU STF-1 subwoofer in a room 20ft long 15ft wide and 8ft ceilings and it puts out a good amount of tight bass. However, in a room the size of mine, this sub is really too small. I am going to upgrade soon to a bigger subwoofer in the HSU line. I bought the sub when living in a 400sqft apt before moving into my house. The sub has very good build quality at 35lbs, it weights more than some 12" subs.
The STF sub IMO is the best subwoofer under 300 dollars. Tight, musical, solid bass, and its only 8" woofer. I have not heard the other woofers you are considering. if you are around mid-michigan, I could consider selling.