As Paul said, any pre-damped drywall is simply layers of standard boards and damping compound. There is simply no mystery to the materials. So the decision to use these pre-damped boards comes down to:
Price (less is better)
Mass (more is better)
Damping (more is better)
Generally you will always be able to field assemble a more massive, more damped and less expensive panel. An additional plus is that field assembly will allow you to overlap seams between the drywall layers.
Sonopan is another variant of sound board, and really has less value in sound isolated construction than you might think.
These sound board products are marketed under many different names. In general they are made from waste material from the lumber industry.
They are light weight and a bit spongy, so the hope of some sound isolation benefit springs forth.
Let's look at the physics of what is available to us in out little soundproofing toolbox. There are 4 and only 4 elements of soundproofing:
#1 we have Decoupling. Having these sound boards on our studs doesn't reduce the surface area of contact, not does it establish the required decoupled mass-air(spring)-mass system we're looking for. So these sound boards do not decouple.
#2 we have Absorption. For absorption within a defined air cavity we want a medium density absorptive material. Sound boards are far too dense for the type of absorption we need so in effect, sound boards do not offer absorption.
#3 we have Mass. The low density of the sound boards certainly don't replace drywall as they are at best 1/2 the weight of proper 5/5" drywall. Sound boards do not offer significant mass.
#4 we have Damping. While the soundboards may be somewhat damped themselves, they do not significantly damp the drywall they are in contact with. Sound boards do not effectively damp what they are in contact with.
So the sound boards find themselves in an undefined category. They arguably do a little but not to the point where we would take up valuable resources to incorporate them.