OK, so if we go with the Omnia sofa, the next question is whether to get the 2.0 or 3.0 density cushions. Since there is a pillow top on the cushion, I was leaning towards the 3.0 figuring the pillow top would counteract some of the firmness of the higher density cushion and that the higher density would hold up better as the sofa aged.

Problem is, the closest dealer is 90 miles away and they don't have a 3.0 pillowtop cushion on their showroom floor.

The store manager recommends the 3.0 for motion sofas (which he will order at the same cost as the 2.0).

Recommendations?

When designing motion furniture, manufacturers are somewhat limited on their spring choices. Meaning you dont have much room to work with so these 2 methods are commonly used. I would suggest Pirelli webbing (2-way) over spring suspension, or also know as Flexolator. If designed correctly; sinous wire will give you a much better comfort(ride). But few manufacturers are willing to make their seat frames strong enough to use sinous wire.
The density of the foam in the seat cushions refers to the actual weight of the foam and not how soft or firm it is. The higher the density usually means a longer lasting cushion. But a low density HR foam will outlast a high density polyurethane foam. Some manufacturers have been know in the past to load their foam just to say they are using a high density foam.

I can't advise you on the cushions, like you've heard there are other factors involved. Anyways, an upholsterer can easily replace the cores when they wear out.

Omnia I believe can properly make a sinuous coil unit.

I was just introduced to Pirelli webbing at Raymour and Flanagan yesterday. Was looking at Natuzzi leather sofas. I understood the salesman to say that Pirelli webbing was the suspension system; no springs. He turned the loveseat over and showed me the webbing and never mentioned springs at all. Just kept talking about how great the webbing is.
So, what's the scoop on sofas utilizing the webbing?

garbage