I started a new MonoTouch project in Xamarin Studio. I tried setting the Status Bar Style to black and the changes don't seem to stick. I opened up my solution in MonoDevelop and was able to edit the plist file no problem.
When I open the solution back up in Xamarin Studio the Application view does not match what is in the file:
I have attached the plist file. All edits made to it were via Xamarin Studio and MonoDevelop. (I didn't do anything by hand.)
I also have the most current build of Xamarin Studio in the Stable channel.