I've got a 3/4, a half helmet, an Arai FF, and (most used) Nolan modular.
When I have ridden with the 3/4 or 1/2, I didn't think my peripheral vision was better.
Getting smacked in the face with debris or rain is NOT a nice thing to have happen on a ride.
After I got hit from behind and had my head smash against the truck and pavement, I never chose a 1/2 or 3/4 again. FF all the time.
'13 Triumph Trophy SE
'11 Tiger 800XC - sold
'08 Rocket III Touring - sold