I believe in that situation the HD shocks are more for fade resistance but they might also have more resistance to movement. They have a slightly larger reservoir too so the fluid does not get too hot or foamy. Nitrogen shocks help eliminate these problems by keeping the oil under pressure, limiting the potential for foaming. I think most shocks these days are built this way anyway.
I'm no shock expert but I have replaced a few dozen of them over my lifetime on my own cars and trucks. For a softer ride I'd go with the standards, but like I said, the heavy duty in the front to control the weight of the engine a bit more might make for a more comfortable ride. That sounds counter to what I said before however, the weight of the engine will cause the springs to store more energy when a bump is hit, this energy needs to be turned into heat which is what the shocks do...isn't fluid dynamics fun?