I have not tried the Attachment approach. I did try other approaches linking and embedding PDF files to various controls. It all boils down to Access rendering the PDF and Access does not do a good job at it. I believe that Adobe does not want to allow Microsoft to render their product in a way that preserves the integrity of the original PDF. At least not without buying Acrobat Pro for each OS the Access FE file is located on.
The supporting DLL file from Acrobat Reader does not allow for a properly sized Unbound Object Frame via OLE. I tried interacting with the control using VBA and looking at various properties. The quality is not good.
Another approach I tried was to use the Web Browser control. This displayed the PDF nicely but did not allow other controls to be displayed on top of the Web Browser control. Also, the Web Browser control did not render to the print spool.
Saving the PDF as a picture or Word Doc seem to be the best approaches I can find. Another one that works is using Illustrator to render a PNG, flattening Fonts beforehand.