Smccul has 2 subs running w/his Maxhemps, 10" Adire xbl^2 subs in a sealed cab (I have one of the same sub). I would prefer stereo subs myself, but my room is too small. I think you will get a more even response, but positioning the subs is still critical. The Adire subs are downfiring, I elevated mine about 1.5' and rotated the cabinet so its now front firing. This works much better for my space. I have 2 large bass traps and 40 sq ft of 3" acoustic foam in the room.
I am experimenting with coupling/decoupling as well. I moved into a place that has carpet over concrete, which seems to be a challenge. I don't think I want to couple to concrete, it doesn't seem like a good thing to do, and I've read some comments suggesting decoupling in this case. I have XRS speakers, sitting on a couple of cheap bamboo cutting boards, with Auralex MoPads between the cutting boards and speakers. I think this works well, better than sitting the speakers directly on the boards. I would like to try using a more substantial block of wood, so I'm looking at some 12" x 12" x 3" Maple blocks used as bowl-turning blanks. These can be had for ~ $20. Then I'll try with and w/o the MoPads...
BTW, the felt surrounds Jim Goulding is selling do work. I tried to work out something with him, but ended up buying (2) 11" x 60" pieces of 3/16" thick SAE grade F3 felt from Sutherland felt co and cutting them to fit. This is easy to do with a bit of careful measuring and cutting with an exacto and sturdy scissors for the top and bottom edges.
http://www.sutherlandfelt.com/?gclid=COCg86_v648CFQfmYAodVCZuMQThere is a $50 minimum, so I actually bought enough to completely cover 4 XRS front baffles...
some pics (I plan on building some sort of subwoofer stand at some point
):