Well, I've decided to do 2.5" duals into a dual/dual muffler with the built-in X-pipe, then dumping that b4 the axle.

 

should sound sweet , get us some sound clips!!

 

Without a balance pipe the sound is a CON in my opinion. I know it isn't an apples-to-apples comparisson, but when I first built the exhaust for my truck (Vortec 350) it did not have a balance pipe. The pulsations in the exhaust, especially at low RPM (idle, cruise, etc.) was irritating. It sort of sounded like a boat.
My firing order is different and my pipes are larger (3") so I think the effect is worse on my truck than it would be on yours. Adding a balance pipe really helped smooth out the pounding pulsation in it. Even later I added two more mufflers to kill the resonance and the raspiness.
It's not hard to install a balance pipe. Put 3-bolt flanges on it to make it easy to disassemble. It's worth the extra time, money, and weight in my opinion.

 

Yea, that's why I decided to go with the dual/dual X-pipe muffler.