Not sure if this counts as spatial dissonance, but I once took an oceanography course in which one week's topic of discussion was coastal zones and potential tsunami inundation (flooding) and the impacts such natural disasters would have on coastal communities. As part of an exercise, our instructor projected a special 3D tsunami inundation map for the Hawaiian Islands and asked a few students to shout out the names of their hometowns so that he could search them in his program. When I told him the name of my hometown (Hanapepe, Kaua'i) the map zoomed close up to show a large portion of the lower Hanapepe area almost unrecognizable because it was completely underwater. In the event of a large tsunami, my entire community would be completely submerged. The juxtaposition of this image with the image in my mind of a very dry, non-tsunami-stricken Hanapepe created what I believe to be spatial dissonance.
On the same topic, another time I think I may have experienced spatial dissonance is when I found old photos my family took of the destruction of our community after Hurricane Iniki in 1992. I was only 2 years old at the time so I don't remember seeing any of the actual wreckage and destruction, most of what I remember of my hometown is how it looked after it was rebuilt many years later. During the hurricane, our house was completely torn apart, splintered wood from telephone polls and car parts were strewn all over the streets, trees had been literally uprooted and blown several hundred feet. Seeing the photos of the wreckage juxtaposed with the image of what my hometown looks like today is another example of spatial dissonance. I wouldn't say there was a consequence to this spatial dissonance so much as a feeling of shock and of course appreciation for the hard work that was put into rebuilding the community.
The Iniki story would be a good example of how Augmented Reality could layer photographs of the past on places in the present and allow for in-depth cognitive investigation of the spatial dissonance you might feel. Examples of programs that show such work are: Time Shutter, http://www.timeshutter.com/, SepiaTown, http://sepiatown.com/, and Cleveland Historical (or any of the other Historicals): http://clevelandhistorical.org/ ...