I have been using this program since it was released. It has never damaged anything and has always improved the performance of my drives.

Apple say that defrag and optimazation is not needed in OSX and that is true ,IF all you do is check you mail each day and surf the net.

If however you do a lot of video work, moving big files about every day then it is indispensable. Not that you need to use it every day, it just depends how much data comes and goes through your drive. Another time would be after a system update. File all over the drive after that.

Also if you need to repartition a drive without losing data then you need to move files to one side of the drive first. This is the only program that does it reliably.

To answer the last poster no it does not do the same as Superduper will to an erased drive. It will make a perfect clone of the drive you are copying with all it's faults or graces.

After using Macs for 15 years everyday there are three programs that I can't live without and are a must.

1. DiskWarrior 2. Superduper 3. iDefrag. And this is not necessarily in the order of importance, it just depends which one saved my ass most recently! Lordy is that the trinity!