You might want to look at the BMW System 6 which seems to be an update on the C3.
Schuberth have always made BMW helmets from the first flip front devised by BMW so paramedics could get to someone to give them oxygen without trying to remove the helmet and break their neck. Over the years each version that Scuberth have made is either behind or in front of the existing BMW version sold at the time. The System 5 could be taken apart and used as an open face and was the last BMW helmet I owned. I now use a Schuberth J1 which looks like an open face but has a protective bar around the chin and literally opens up your viewing experience on the bike. Bell Helmets used to have a saying: "If you got a $10 head wear a $10 dollar helmet and Schuberth have always come out in tests as one of the quietest. They also make helmets for other markets including the fire service, construction and the airforce as well as F1 so there R&D is pretty good.
