Buttkicker experiance? with high end sub?

Hi all. I'm about to buy my first REAL subwoofer. Something along the lines of an SVS PC-ULTRA or similar from another brand.

In my research over the last couple years (yes years) I discovered "buttkickers" and their competitiors. People seem to like them.

My question is, they have a very low range where they produce "sound"(i'm talking about that inaudible range now). Do I want to avoid paying lot's of money for a sub that digs down just as low? or is overlap preferred?

I hope that makes sense, I feel it's poorly worded.