Cheap? Well it can be I suppose... not everyone is as insane as me. Mine will run $2500 once it's all said and done. That's about what my two SVS subs cost. It might be a little less depending on if I end up needing a x-over and/or two amps.
I never had a problem with my Velodyne HGS-15 traveling throughout the house and Angibug complaining... but with my two SVS subs... if she's at home she's gonna have something to say when I take a pee-pee break or get done with the movie. I know what she means too... when Chelsea and her friends are out there and we're inside, it's unbelievable. It sounds like some serious thunder. I could hear faint thunder in the distance with my HGS-15, but again not a problem. With the two SVS subs... it's like right on top of the house... loud. Every now and then something will shake or rattle. Angibug made the statement one time that the house was gonna fall apart one day because of that room. Maybe so with the IB's.
Darren stated his IB is not really any worse than his regular sub, but he has a lot of insulation in his attic too. ThomasW has recommended I put insulation in mine.
Anyway... I'm getting somewhat off topic.
My reasoning for trying IB is to get the supposedly ultra clean low response down to 10hz or so, but I've heard on more than one occasion that IB doesn't always have the same impact as some traditional subs. But then I've heard it can if you do it right and have the right conditions.
You ask for experts, why did I even chime in?
I think Chrisbee has a way with words that describes IB like no other. I'm sure he'll chime in and share it with us.