Hi Mike,
I very recently bought a Sportster - my first Harley. Have ridden Japanese in the past and always worn full helmet. I spent a few years working in maxillofacial surgery and have seen too many horrible disagreements between human flesh, bone, teeth and asphalt. By all means wear a 1/2, 3/4 or skull top and look good when you're stopped but when you're on the road - wear a full face and keeps guys like me and my mates doing crosswords.