Personally I would go with 7.1 and have been with 7.1 for over 2 years now. I am a loyal HK receiver owner and thus love their logic 7 technology for music etc...where as DD EX makes some difference...not a lot but once in a while it will surprise you. For example....rivers...you can hear the water out of the 2 extra speakers for a while...where as with a 5.1 you will probably not get that extra "ambience".

MY 2 Cents.

-Tarun

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Denon 4308
M80x2,VP150,EP600,4xQS8