Building new front stage!!!

[Cisko213]

Hi guys and gals. I'm currently in the market for a new front stage system. My room is 21x17. The TV and front stage is set up across the middle of the 21'wall. This room also opens up too an open vaulted kitchen. I have the couch about 12' back. I use a onkyo 818 reciever. I have a JL F112 subwoofer. My surrounds are in the cieling and are generic but sound really good being pushed by the onkyo. My current but broken fronts are B&W dm604 s3's with the same series but smaller center. Bought about 8 years ago. My TV is a Sony XBR 950. I had this place remodeled so when I get home and on my computer I will post a pic so you can see the layout. My question is in upgrading the front stage with three similar speakers. The TV sits about 50" up on the wall so if I wanted I could place three towers in the front. My question has been with the Sub I have and I'm sure people notice this with other good subs. Are towers really needed. Currently I have moved my center over to my left channel. And left my right tower where it's at. (My left tower crossover is no good, but I ordered a new one if I want to sell them). I set the crossover at 80hz. Anyways watching Oblivion. I couldn't notice a huge difference the sub takes over so much of the low end. That the rest is taken care of. Are towers really required. When comparing speakers will the towers compete with the CMT-340's?