This tank is going along a wall and the right end of the tank is open to a set of tri-fold doors that open to the back yard. When the doors are opened the 4' end of the tank will be viewable from the back yard. So I didn't want overflow right there in the view.
I also think that in aquascaping a tank for it too look most natural, things can't be in balance. Things have to be offset an unequal. Moving the box off center does this. In my mind the right side of the tank will have a really large island structure. The left side of the tank will have a small free standing island. This will leave a channel from the front of the tank to the back. The channel will be off center and at an angle. This way the channel doesn't lead the eye directly to the overflow in the dead center of the tank -- At least that's the theory.... We will see once the rock goes in.
Also the whole back wall of the tank will be clad in slab rock - so it should make the overflow dissappear altogether.