low poly for iOS terrain

I am working on an iOS game (iPhone 4) and experimenting with the terrain performance. I read a suggestion to change to pixelError to get a dynamic low poly count in the terrain engine. When I change this setting, it works within Unity but when I load the game onto my device the pixelError setting doesn't seem to be being used, i.e. the terrain still looks high poly. Does the pixelError setting work on iOS?