Thanks Erel.
Just for the experience I recreated a map view on reorientation as you suggested, preserving the key elements as Process Globals as well as the overall WindowState (remember those?). The logic within the Activity_Resume event is not quite as simple as one might imagine but it can be made to work.
My conclusion is that it is not worth the effort. The user experience is degraded as even over high speed wifi there is a significant wait for the map to redraw, this is particularly true in the case of my app where I was exclusively using Satellite view.
iOS is so much better in this regard.