To piggyback on some of the comments bestbang4thebuck made (and speaking as a fellow LFM-1 owner), the number of recordings -- and even beyond that, the types of music -- that have much musical information at or around 20Hz is somewhat rare. Organ peddle notes are one of the first examples that come to mind, and a sub or speaker system that can delve into these nether regions can really help you feel the pressure wave. But in terms of 90% of what I listen to, the LFM-1 goes plenty deep. This includes all sortsd of music as well as big explosions and other effects on movie soundtracks.

IMHO, how the sub interacts with your room will really drive how musical/natural it sounds and, more importantly, how it does or does not integrate seamlessly with your mains.

As bb4tb mentioned, room treatments can help. Beyond that, a product like the Velodyne SMS-1 or Behringer Feedback Destroyer can help optimize the LFM-1 (or any other sub that matter) to your room. I have yet to buy one, but plan to in the next month. From what I've heard, it takes a sub like the LFM-1, Hsu, etc. from good to great.