Another thing to keep in mind about the Space Navigator is that it is not a mouse replacement. The mouse is still being used to select things with one hand while the other hand moves the Navigator around inside the preview window.

One of the utilities with the Navigator allows configuring the amount of pressure required to move in each axis. I forget exactly what I changed, but it improved how well it works by adding pressure to axis movements I didn't want so that I wasn't accidentally banking when I was trying to move along one axis.

I hadn't even considered using it in Photoshop, but I suppose moving and zooming in on a large image could be easier.

My visual indexes of Poser content are at http://www.sharecg.com/pf/rgagnon