Well, no joy, unfortunately. The Que box uses a mutant chipset (QBP-2) that seems fussy about what IDE device is connected to it. Apparently, not all IDE-Firewire bridges are made equal (big surprise, eh?). It works okay with an old 2x Plextor DVD writer I happen to have, but does not work with the 18x LG DVD writer that I really wanted to use. I borrowed another firewire enclosure with an Oxford 911, and it works with the LG drive just fine, so the drive itself is ok.

Googling about the QBP-2 reveals that I am not alone in this experience. Oh well.