I received my LSP-12 last week and was able to get it set up and tuned with Audyssey over the weekend. This is the second LSP-12 for my setup.
I have them both positioned at the front of the room, equal distance on each side of my TV. I would have placed them opposite of each other in the room but my receiver (Denon AVR-2112CI) only has Audyssey MultEQ XT and therefore cannot tune two subs independently. So, it was therefore necessary to have them setup as I do in order for this version of Audyssey to do the best it can with them.
I haven't experimented too much yet with differing source material but just from some basic Netflix watching, it's already quite evident that the output is increased. Also, I often sit in my recliner in one corner of the room and from this spot (not at all directly in front of the TV), the sound is a LOT better. Smoother is the best word for it.
I started with one LSP-12 back during their first $170 sale (November 2013, iirc) and it was a step up from the Dayton SUB-1200. I was excited to add the second LSP-12 and I have no regrets so far and don't expect any either. I have a large open room and this is the first time that I've actually had enough bass in my movie viewing that I wasn't disappointed. It's not movie theater quality by a long shot but it's a step in the right direction. For a total of $340, I'm very satisfied.
Thank you to everyone here that has given their input and offered advice. It pays to ask questions, research, and read other's reviews.