[lsamberg]

I don't believe there is a problem with pulling a PDF into InDesign and then exporting the ID document back to PDF. I use ID a lot and my gut feel (no real data) is that it maintains the PDF definition of the diagram and exports that directly to the final PDF (i.e. no copy machine effect).

The other approach that I usually use is to just export as a JPG and do the same thing -- the JPG is more flexible IMHO since I can pull it into many different programs (like PowerPoint).

Either way there is an extra step beyond just importing the graffle file (like you imported the Visio file) but beyond that it is a pretty clean process. ID will detect whenever the linked PDF or JPG changes and you can just click to update it.