I have an AGV K3, original with a clear visor. Purchased a tinted visor an worked great until my first encounter with heavy rain and fog so thick that the visibility was around 5 meters (in a narrow colombian mountain road). So I had to ride with the visor up (rain drops felt like needles in my face) and with the help of a nice guy in a mazda that follow me and another biker, we reached a safe spot to park. As soon as I got home the clear visor was back. Sometimes bad conditions are so sudden
that you can't change the visors on the road. Probably the best option is to have the internal sun visor, although I don't fancy it.