Viewer Comparisons

Pagemark Technology has published a comparison of the performance of different XPS viewers (XPS, PDF). The report covers XPS viewers from a number of different sources:

Microsoft XPS Viewer
Informative Graphics Brava Reader!
NiXPS Edit v 2.5 
SANAtech  XPS Viewer v1.0
Adobe Acrobat 8.1
Software Imaging XPS Viewer
Pagemark Technology XPS Show

and includes a feature comparison, rendering results and performance assessment.