I've changed my mind. It is just a 109, but with bundled software. I noticed that all the Pioneer drives listed on their web site say the same thing; namely, that Quiet Drive utility is downloadable. But I believe it will only witk when the drive has A09 firmware.
So then I downloaded the current 509 firmwareâ€”which is still 1.55. After unpacking the exe file i discovered the firmware is the same as the 109 firmware (same numerical name, that is).
So I guess it is just a retail 109 with Uled software, or whatever.
To complicate matter, Meretime sells an external 109 (firewire, usb) that they claim has Quiet Drive technology.
I'm not sure why the 509 doesn't have a 1.57 firmware, but as Chef notes, it wold be a simple matter to cross flash it.
The Best Buy price, by the way, is only $60 after rebates.