Comment 9 for bug 664335

Using PDF 1.5 is unlikely to be causing issues with Adobe Acrobat. PDF is designed to be forward compatible. ie if the PDF file contains features that the reader does not know about, those features are ignored while the rest of the file displays correctly. The PDF 1.5 features that cairo supports are not used by Inkscape so even though the version in the file is 1.5 it is only using 1.4 features.

Only very old versions of Adobe Acrobat don't support PDF 1.5.
  Acrobat 5 (2001) -> PDF 1.4
  Acrobat 6 (2003) -> PDF 1.5
  Acrobat 7 (2005) -> PDF 1.6
  Acrobat 8 (2006) -> PDF 1.7
  Acrobat 9 (2008) -> PDF 1.7 + extensions

There are many other differences between 0.47 and 0.48 that could be the cause of your bug. Usually problems with opening PDF files are a cairo bug since cairo should never generate an invalid PDF file (unless cairo returns an error status).