If you are using another Silverlight XPS viewer you may want to talk to its developer. The only option we are aware of is firstfloor, however just like SilverDox it does not support full XPS spec. In this case you may be better
off with SilverDox because we can 'guarantee' that all XPS features we produce are rendered accurately.
You should be able to view XOD files in SilverDox or WebViewer (which also supports HTML5 and Flash besides Silverlight - http://www.pdftron.com/pdfnet/webviewer/demo.html) without issues.
You can learn more about WebViewer and SilverDox here:
This avoided TIF (as now they are PNG) and texts HEX code are correctly (we don't have problem 1 anymore).
One remaining question is how does the SilverDox viewer handles VisualBrush as it's an element not supported by Silverlight. Does it skip it?
You are probably experiencing a bug in Silverlight itself that is triggered by rotated text. We reported the problem to Microsoft some time ago, but until they fix it (which unfortunately seems unlikely) we have implemented a workaround on our side that converts all rotated text to paths. You can enable the workaround by using the --silverlight_text_workaround in the command line tool, or SetSilverlightTextWorkaround(true) (in XODOutputOptions) in the SDK. The text itself will still be selectable and copyable in SilverDox. This option is not on by default because it is not necessary for our HTML5 or Flash viewers (that also open XOD files).