Well Tom knows quite and bit, and he could be correct. I am only going from the info that I have heard from around a dozen individuals who know the industry pretty well, and a few australian websites I ran across while searching the web for high end struts.
Regardless, all of this is not related to the fact that the link I posted at the top is to one of the absolute finest suspensions systems in the world . If you want a race car suspension for you car, then that is where you should look.
Interestingly enough the Powerflex has components from both Bilstein and Ohlins, who are probably the two finest suspension component manufacturers in the world.
Arguments to the contrary are worthless, you will simply not find anything better for the GC8, GDA, or anything else. Yes they are expensive. But for what they are, the price is more than reasonable.