This program would be awesome if it was able to flash back and forth between the two images, one over top the other, sadly though, it only shows them side by side. I also don't totally understand the differences between the 'Show' viewing modes. It doesn't seem to be able to pick out differences with flattened pdfs, it simply highlights the entire pdf as being different from the other one. Maybe I'm just using it wrong?

We actually make use of similar (but clunkier & infinitely more expensive) software doing packaging design for our QC process with our digital proofs. I was really excited when I first saw this, but for what we do, the functionality just isn't there. Hopefully improvements come for this now that it's up on LH.