Thanks for your comments, iqt. Actually, I've used both programs myself, but for me, it's really hard to tell which one affords better overall performance. Of course, for anyone watching this thread, JKDefrag is free and PerfectDisk Pro is commercial.
Just a day or two ago, I received an upgrade notification and link to PerfectDisk 10 Pro. I believe this was an advance release to paid subscribers, but it may be available to all now. It will be interesting to see how this new version preforms.