No, Chris; as mentioned before, "all channels driven" isn't a realistic standard outside a test lab in the real world of home listening. When 1 or 2 channels happen to simultaneously hit a 105dB peak(which for most users may never happen, since reference is considered too loud for home use and a 10dB lower setting is common)the other channels aren't at that level.
I know this is an exception, but I have seen it with a friend of mine: he absolutely loves music on "7 channel stereo" (which I don't like personally); he does have the same speaker all around. According to his receiver specs, this means: center channel= a sum of main L+R, and the rest is split equally between all L and R speakers.
So it all comes down to what your intentions are, and you budget.