Now that you've pointed out the 5-channel amp, I don't think there would be any audible difference between that and the 2-channel. Unless you want to use the 2-channel in bridged mode for double the power. I can't imagine driving that kind of power into my 80s. First, I'd go deaf. Second, I think the 80s would vapourize \:\) .

House of the Rising Sone
Out in the mid or far field
Dedicated mid-woofers are over-rated