7.1 vs. 5.1 - Meaningful difference?

Dredging up an old thread.
Thinking about why my Lexicon won't do 7.1 analog bypass. I'm set up for it otherwise and now in the world of blu-ray 7.1 is a reality.

I have been using 7.1 for four years. It has more effect than I would have anticipated. My Pre/Pro matrixes or synthesizes 7.1 from all 5.1 source material, and now most Blu-Rays are 7.1 discrete on-disk. When the rear surrounds are off, the soundfield thins out and is thrown forward; the soundfield doesn't feel as complete or enveloping without those rear surround channels.

I found the improvement so substantial in my smallish HT room that I can't say it's simply a subjective difference. I upgraded the receiver and disk player to Blueray and added two more of the same speakers. Even with 5.1 media and cable the matrixing my receiver does with the side and rears is surprisingly well done.

When I bring it down to 5.1 the sense of space is dramatically reduced and the fronts and rears have a more discrete presentation that is clearly less enjoyable.

I recently helped my in laws with a 7.1 upgraded using very inexpensive components in a small space and again, after the room correction was run the improvement was very noticeable. I would guess you may have issues with the processor or the setup.