One way or another tinting the front does reduce visibility, especially at certain times of the day/night. I would suggest that some of it could depend on the type of roads you frequent. I live in an area where there is almost no lighting on streets so things get pretty pitch black, but I know more urban areas have well lit roads and in those areas tint makes less of a difference. I would suggest you take a look at some cars that have everything but the front tinted - the front looks about the same as the rest simply because there is less light inside the car. I'm not sure you gain a whole lot by adding a light tint (anything 40% and up).
Your car, your choice - tinting can always be undone.