I can't remember if it was this burner. But, I remember someone having one of the burners I have asking what the slowest speed of CD-R/W media their burner could burn. I found some old media and my AD-7200S claims to be able to burn it at 4x. Which is a tiny bit odd as it's labeled as 2x, but who knows.
Hmm, okay, another piece of media it clains to write at 4x shows different behavior in my DH20A3S. That drive claims to write on media at 4x and claims not to be able to burn the second piece of media. The media it won't burn is the 2x (labeled) media. So, I'm guessing the AD-7200S will burn (some, maybe not all) 2x CD-R/W media at 4x (not tested) while the DH20A3S will not touch 2x media.
I hope whomever asked the question finds this useful. Not that I mind digging through my boxes of old media.