I know it is not supposed to make a difference, but did you try and 'aim' the driver in different directions after you placed the enclosure? At this point, it may be worth a try...
Funny you mention this, as I was going to bring it up. At least in my room, the driver direction makes a HUGE difference. I'll explain in a minute.
So, thanks to jakewash I burned the CD of the frequencies from RealTraps tonight, and just finished spending 5.5 hours down here messing around. It's a pretty cool thing, the driver extension at 10 hz is pretty comical. Anyway, it let me graph out my findings and what it would accomplish to place the sub elsewhere.
To make a long story short, it was pretty much a bunch of wasted time that the sub crawl didn't tell me already. I did actually find one position that the sub flattened out a bit in, but listening to it with some U-571, I just didn't like it as much, so I put it back where it was. It's amazing to see with the SPL meter just how much one foot can make a difference. Right behind my seating area to right in front could be a 15 db swing in some frequencies, and then in another range it would be the exact opposite. It's no wonder people go mental over this stuff.
The point I wanted to make about the driver direction was that in one place I tested, just by turning the sub 180 degrees, I picked up twenty-four
decibals at one point around 57 Hz I believe. With the sub in the "bad direction" I was getting 59 dB (lol) whereas it was 83 the other way.
I do have about 10 dB lulls at about 56 and 78 Hz, which was the same pattern no matter where I put the sub, so it has to be my room. According to SVS's graph the sub does dip a bit at these points, so that probably contributes a bit as well.
One thing I did find odd, was that I am down a decent amount as well at about 95 - 110 hz... I don't know if this is just from coming out of the range of the sub, which level was probably set a bit too high, but I don't really have another explanation for it as the W22's should handle that frequency with ease.
I think the next step is going to be a couple bass traps in the back corners of the room and maybe some panels on the walls. Can't hurt I guess.