I selected "Add a sub" option, admittedly without reading all the other responses, just because when we added a sub it really helped. We run a little bit of everything in our PA now, and adding the sub let us do that. We ar running two Behringer 15s for tops, and the sub is an 18 inch Behringer. Adding the sub allowed us to get a little extra thump in the mix without having to add any size IE bigger mains. We have two Behringer powered monitors with 12's in them I think.
But I am no sound expert. I've done it in the past, but I have never heard that anybody had trouble hearing us at any show we've played with the gear we have. It's small and compact. I carry The sub, cable box and mic stands and my cabinet in my Ford Escape, and the singer carries the tops, monitors and speaker stands in his SUV. I covers most places we play.
BnB