If you use lines merge or transparency in your AutoCAD drawings XPS is not a good choice because AutoCAD itself will rasterize the Output so you end up with an image based PDF basically. Typically the file size is larger and when you zoom in close the diagonal lines and such are not as clean looking.
The XPS problem is AutoCAD's fault and it does it to any XPS based driver.
If you would like to do an etransmit of the dwg and email it over to me at email@example.com
I'm already working with their programming team on some other AutoCAD drawings. We specialize in AutoCAD to PDF and DWF conversion and use Tracker's products in our products.