[jahewson]

> PDF → XPS → PDF

That's not what's happening unless you have a printer which directly supports PDF. Most likely what is happening on Windows is either:

    PDF → XPS → PCL
    PDF → XPS → PostScript

Depending on the printer. Which makes far more sense and is analogous to what OS X does:

    PDF → Quartz → PCL
    PDF → Quartz → PostScript

There's really no notable difference between these two approaches as both Quartz and XPS are based on the same printing model as PDF. Don't confuse Quartz with PDF just because it offers import/export to PDF - Quartz has its own internal imaging model.