I'd like to be able to take a published PDF of a drawing and compare it with another iterration of a published PDF of the drawing. This would better support review situations where a markup doesn't show enough information. There're also times when someone might want to sneak something into a drawing upon change that isn't readily caught during that review. This would flag that delta.
I know that it would be difficult to compare PDFs originating from different content such as Office document formats. However, providing this capability for PDFs created from Creo would provide a lot of value to the review process.