Lotsa Blender love goin on here.  To get back to the original question, it's clear that you won't ever know what software vendors are using unless you take a official poll somehow, or interview them privately.  Most Renderosity vendors don't participate in forums, especially in threads dealing with techniques or software debates, because they don't wanna lose sales.  The last thing a vendor wants is other modellers to know how to make things, because then they lose their ability to sell things.  They also won't usually debate or post opinions about software, because that usually gets people mad if your opinion isn't the same as theirs on their fav software, so then you might not buy their products.

Imagine a guy who sells bras for Poser girls coming in here and saying he uses application X, because it's better than Blender for this or that, etc.  There'd be a dozen fanboys who wouldn't buy his products.