Of the years I have been tinting windows, I have only tinted about 4 cars with 50%. When the customers came to pick up their vehicle, they asked why I had not started tinting their car yet and why I called them to pick their car up.
50% is hardly noticable in many light conditions depending on film, and they didn't even know their car was tinted.
With that said, even though I warned them how light 50% is, they wanted to be legal in MN. I've tinted the same customers a couple of years later on different cars, and they did 35% and were very happy.
Thought you might like to know others experiences. Of course this doesn't mean that 50% wouldn't satisfy you, I've just never met someone with legal tint in MN because it looks like clear glass.
In my experience, 35% seems to be the happy medium for most people. If it would help you out, I could email you pictures of cars I have tinted and you could decide for yourself what looks right percentage wise.