I'm just your fellow community member. It does seem like a great idea, especially considering that the SpaceNavigator was compatible with Virtual Earth, when it was still around.
Hopefully, when Read/Write World opens up their RML viewer source code (hopefully sometime in 2012), the 3DConnexion folks can add support for their accessories. http://bit.ly/readwriteworld
Out of curiosity, have you only tried your SpaceNavigator with the Silverlight Photosynth viewer or have you also tried using it with the Direct3D Photosynth viewer?
You can find the link to the Direct3D viewer on the lower left corner of any Photosynth's 'view' page.
Here's an example of the difference between the Silverlight viewer URL and the D3D viewer URL for a synth: