I've had two LZX drives and they have been in my experience, mediocre.
I bought a Fujitsu 3184..18GB with an 8 MB buffer, and what a drive. Cool, quick, very little noise. I now have 2 18 GB and 2 3367 36 GB models. I can't speak about IBM 15K drives, but concerning 10K....Fujitsu builds a first rate product.