Only applies to 5.1/6.1/7.1 content - you'll notice during the panning sequence... that's why its important to have timbre matching - same woofers/tweeters/cabinets used throughout all 5 channels.
For mediacorp programming, most likely you'll be running the Dolby Pro Logic/II, DTS Neo, CS II surround modes to have a "pseudo" effect. You won't get problems when running in this mode, but somehow the speaker that has its timbre mismatched will definitely sound out of place.
Another thing is how well the amp does this is pretty depedant on the DSP chip. Yamaha seems to be the best at this. Denon still sounds abit muffled (again, its a personal POV - others' listening tastes might differ)