Yes, I posted a thread on my findings a while back about this.
There were notable changes. You see, I was a halo 2 modder and I kept ftping back and forth .map files all the time. After my defrag, I think I shaved about 10 seconds off the time it took for Halo2 to load into cache.
Also, I think XBMC booted a second or two faster.
I used the backup, format, and replace backup method.