Using 2 Subwoofers

One of the advantages of using 2 subs is you can get away with smaller drivers.
A room that sounds good with a big 12, or 15" sounds even better with 2-10" subs.
You pick up alittle speed, and your room does not have to compensate for such nodes (trying to support 30hz clean).
A stereo 50hz, sounds alot cleaner than a mono 30.
I once had 2 Klipsch 8" powered subs hooked up, and they sounded better than all the premium single (12&15") subs I have owned, especially on 2ch music.
Just my opinion, I am no expert by anymeans.

I agree with Bob. To restate and expand on his point.

If you have Audyssey or similar digital room correction (DRC) in your HT electronics, a single well chosen sub (SVS and JL are highly regarded for dual music and HT use) should be more than enough for your space. The DRC will correct for destructive room effects, so you needn't worry about addressing that issue via strategic placement of multiple subs.

The ability to address room issues via strategic placement is the primary reason I'd choose multiple subs. In this respect, DRC or multi subs are an either/or solution to the same problem. You can use both (I actually do so, but for quirky system and room specific reasons), but you usually needn't do both for smooth FR in the deep bass.

While it's also true that multiple subs will - all else being equal - provide higher output for any given distortion level, in your smallish space a single high quality subwoofer should not be remotely stressed into audible misbehavior.

Marty

I'm going to be a bit contrary. I have a similar sized room and it is also open on one side. I have a JLf112 that I placed in front just inside my right main speaker in a position commonly recommended byt JL , THX, etc. I ran the JL equalization and the pioneer system and decided the JL system resulted in slightly better performance. I have on several occasions tried listening in all areas of the room and while I can hear a difference, in my case is is not huge and frankly no big deal (YMMV or course). I would suggest trying one and seeing what you think. Than again I also find that not having a matching center ( I do, but ran non matching for some time) was less traumatic than I thought it might be.

I own two 15" non-ported audiophile subs and have them placed on either side of the room. One in back and the other in front next to my towers. For two channel music I turn off the sub in the back, because I prefer all the sound coming from in front of me. For movies both subs are set to levels that make you feel like a neutron bomb was dropped on my house.

Therefore, I recommend two... you can always turn off the second one.