I successfully updated mine with the .img and it didn't change anything on the info menu so I don't think you can tell. Whenever you change between menus there will be a black screen as they change, if you see a white line on the edge of the screen it hasn't been updated.
Speaking of which, has anyone successfully updated the firmware and tried Frodo? For me the colour palette is messed up but I'm not sure if the firmware update caused it having not tried Frodo before the update.
Here's a crappy picture of the problem.