I created and example based off of the spherical-mercator example example and placed it here. I made the bing road layer the default. If you zoom in on a location and then switch to a google layer you'll see the map go to full extent and then zoom to the correct extent. It happens very quickly but it is a distraction. I've tried several hacks to get around this but none of them work (delayed opacity, calling setMapObjectCenter before setting visibility).
Anyone willing to figure out (or already know) how to eliminate the flicker/animation? Note that this is only an issue the first time you select a google base layer. Subsequent switching transitions beautifully.