I think it is room dependent and, well, personal preference. Some here with smaller rooms haven't noticed much advantage. If you have a large room, 7.1 may sound better.

Oh, and I think with some of the newer HD sound formats, those mixed specifically for 7.1, don't get down-mixed to 5.1. So, you lose out on some information. Pity, really.

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"Nothin' up my sleeve. . ." --Bullwinkle J. Moose