I’ve tried both PerfectDisk 7 and Diskkeeper 9.
Diskkeeper is substantially ‘faster’, but as mentioned, it will typically take more passes to thoroughly defragment. PerfectDisk appears to do a better job of reorganizing freespace, but it’s not as complete as touted on their website. And, it does take a considerably longer amount of time to perform a defrag.
Funny thing is … Diskkeeper and PerfectDisk analyze the same hdd fragment state competely different reports. After defragementing wtih PefectDisk, Diskkeeper analysis will tell me it’s still 20% fragemented, etc. - while PerfectDisk graphic looks fine. Then, after defragmenting same disk with Diskkeeper (which will state 0% fragmentation), PerfectDisk shows a different story. Etc.
As Mike mentioned, PerfectDisk seems to do a better job of reorganzing free space. The one thing that’s missing is an actual tab (as in Diskkeeper) to show the analysis results - ie. you have to analyze one disk / partition at a time only if you wish to actually see the report.
I’ve been using Diskkeeper for several years. The strangest things that have happened are things like the taskbar going blank after scheduling boot-time defragmentation. It’s been a great program - esp. with the set-it-and-forget-it options and MFT configuration suggestions, etc.
I will give PerfectDisk a try for now. I can already see it lacks some of the features of Diskkeeper, and its interface could be improved. But, I’m curious how it will continue to perform.