I hear ya Ron.. It's too easy to over do it at either end of the spectrum.. I must admit, I still do not have subs worthy of mention, and as such, have yet to really experiance the complete sounding home theater system.. Even so, I do not hear anything 'bad' added to the M80 sound.. From the results so far, adding quaility subs will just improve the bottom end..
And yes, I too like the added height, bringing the tweeters up a tad over my head now when seated..

LFE ! The rest is just details..