Back when I was shopping around they only had the LMF-1 and the LMF Plus. The difference between the two seemed rather negligible to me and the marginal benefit gained from the plus didn't seem worth the additional cost.
Room size is about 20'x13'. The room definitely feels small for the sub, no question about it. Until I hunted around the apartment for the 'sweet spot' the walls would vibrate and the windows would rattle on medium vol settings for the sub
However, once properly placed, the BEST way for me to describe the sound would be to call if TIGHT. You feel the pressure in your ears, but it there is NO boobminess that I can detect. The sounds starts and ends abruptly. I have auditioned a few subs, (not v. high-end ones mind u) and this sub sounded the best to me.
One thing I must mention: the first sub they shipped me was defective
But the customer service was extremely helpful, paying for all the shipping and sending me a new one. They tried their best to help me fix the sub over the phone. After fiddling around with voltmeters and screwing around inside the sub for sometime, we both decided that it just couldn't be fixed and they sent me a new one without any problems.
Highly recommended!