well I just up graded my lod LaCie from a 12X4X32 to a new Sony 40X12X48 burner in the same LaCie case, the drive works wonderfully after i changed drivers in OSX 10.2, I can burn a cd in under 3 minutes. I love it.
When I had the 12X burner in the case it only spit out a couple coasters, but that was due to the media, so I would recomend LaCie, or any others, but be warned look at Apple web page for compatibility because most of the new drives ie 40X and above arn't suported.
Also check the acutual drive mechinizim in the case, some more name brands are better, but a little more expensive.