I have used a number of these discs over the years, and still do for 2 things, ...various phases of component, cord/interconnect and speaker break-in between music playback cycles and "system refresh" every 10days-2 weeks. They do work to greater or lesser degrees depending upon the disc in question, the algorithms used, etc...to restore the clarity, air, etc....to the system.
Perhaps it is the composition of my system over the years, the type of components, the fact that all cables I use of any kind have alot of ribbons and/or many mixed guage conductors in them, however, the best one I've found to date is the Isotek System Enhancer disc; specifically, I use Track2 (large systems, full-frequency/bass). The guys from Esoteric and someone else turned me onto this several years ago and it helps alot in both break-in as well as 'system tune-up' usage. The PAD RevB disc I have from a few years ago works well but at least for my system, does not yield the same level of results for either break-in or tune-up as the Isotek disc.
Agree with Sunnyjim that the changes are never earth-shattering with either disc; it's about bringing the subtleties back to the system,...remove any minor buildup of magnetic grunge, restore the air/transients clarity, etc.....
Personal opinion,...no way the PAD/other discs is worth the $119-$150 asking price I've seen. The price used to be a lot more reasonable. I think the same person who sets cable prices dreamed up the revised retail price on this disc. $50 top-end is about what these things are worth (again IMHO). The Isotek cost alot less when I bought it and it brings alot more to my system. I have a RevB disc that I would part with,...let me know via email if interested.
The Isotek disc is definitely worth breaking the cellophane! I've used it for 4-5 years and am very happy with the results.