I'll echo the comments about the tight fit. I found a Sony CD burner that was shorter than most of the IDE CD drives I could find at the time.
I'll also confirm that adding a Deneb would give you a variety of choices. I haven't tried any USB CD drives on the Amiga but I don't have fond memories of using them on a Mac!
The IDE drives are the cheapest solution but Deneb gives you a whole bunch of options. I like having both the drive and USB options on my 4000D.
