Is two Subs better than One?

What is the general consensus? And why?
OK, if you are in the US, where bigger is always better, 2 is better. Anywhere else, depending on room size of course, one well choosen sub is fine.
2 Subs Sound better to me. After all the opinions I thought I would buy a second DD15 Subwoofer. After setting it up but not yet finely tuning it; the volume needed to be decreased to synch with my Wilson 7's. I could definitely sense a fuller better balanced base. The mid and upper frequencies were more focused due to the fact that base appeared to fill the room better. With the base originally localized more to one side, the Wilson midrange on the opposite side did not feel as intergraded.
I guess bigger is better.
I added a ACI Titan II LE as the second sub to my system and I don't think I will ever go back. My room is 13.5 x 17.5 and the second sub just make everything sounds better from 2-ch music to 5.1 HT movies. I'm using Anthem processor which has 2 sub outputs so hook-up is very easy.
Lynhnn, just curious, but at what frequency to you cross over your subs to your main speakers?