Hi Scott -
I read your question - but not any of the answers so I hope there's nothing superfluous here.
In my opinion - you simply cannot be in a large venue without a sub. I just got back from a wedding now (its 1:20AM) where I used one. Its a great pain in the *** to lug around - in fact I've started hiring somebody to set up and break down my equipment just bc of the sub! It costs me $75 but the big sound is worth every penny.
I've only started using in a month ago and everybody's raving about my sound. They don't know what it is - they just know that I have a sound noone else can beat.
Chony