I'd be curious to know if there is significant safety advantage between half and 3/4 helmet. I don't believe there is. I believe my full faced Arai is much safer than my half helmet. If I'm going to skimp on safety, I'm keeping me ears and face in the breeze.
I do wear my mesh always. Non-black mesh with shorts and t-shirt is quite comfortable. The mesh allows the breeze but the sun is blocked.