I read the ARSTech thread and have to agree with the person who mentioned that they listen to a lot of MP3 files so......do you want them at the fastest part of the drive.....no!
I never choose to defrag or optimize for frequently used files myself. It doesn't seem to make a lot of sense and I think it is a poor idea. But what do I know.
Another reason I'm holding with 10.2.8 until the dust bunnies clear with Panther.
I'm not the adventurous pioneer like I used to be with Apple's OS's, I'm kind of sitting in the back of the stagewagon until the arrows stop hitting the side of it.