If you're using the bass management in the Integra 80.1, I doubt that you'll hear a ton of difference between sub positions - unless you happen to pick a really, really bad one. I've had my pair of (Rythmik) subs in five different spots - including those between, outside, behind, and ahead of the mains - and never really felt that there was much to complain about in any of them after the Audyssey set-up with my recently installed Onkyo prepro.
I spent the first week after installing the Onkyo experimenting with subwoofer placement and set-up mic placement. The result from many dozens of sweeps indicated that sub placement (all within 4 feet of the speakers in my circumstance) made little difference in the end result - that I could hear, anyway. I know that this runs 180 degrees opposite the experience with non-EQ'd subs, but that was how it played out in my case. In fact, I believe that you're more likely to hear differences between different mic placements with the subs in the same spot, than you are between different subwoofer placements with the mic in the same spot. IME, anyway.
BTW, I ended up using position # 5; My Ohm 100s sit atop the subs (on a special-purpose speaker platform). This was chosen not for sound optimization, but to minimize the footprint. Other than slightly altering the imaging/staging, this position sounded very much like the others - and opened up floorspace.
Good Luck.
Marty
