A open face helmet has more side vision than a full face helmet and you can turn your head further around than a FF helmet, you might dis agree with me but I do have 4 helmets, 2 full face, one flip top and one open I wear and for vision wise the open face is the best to see what is happening all around me and it don't worry me what other people opinions are which is safer or not and as I say I been riding now just on 50 years and I feel safe in myself in what ever helmet I wear, but I prefer my open face to the rest, for comfort, vision and quietness, but the hardest thing is finding a helmet that is quiet without wind noise without wearing ear plugs and really you don't know what effect that will have trying on in a shop and long term fitting, my motocross FF helmet and OF helmets are so quiet but my FF and flip top helmets make so much wind noise and they weren't cheap helmets and fit nice and snug, I hate wearing ear plugs as I like hearing what going on around me.
Most helmet producers will have data statistics saying which is best but really I have never seen any medical or GOV statistics to prove other wise what is safer or not, anyone can make a opinion but facts as they are just not out there to prove how many lost their lives from wearing a open face to a full face its just not there or how many died from head injuries, as I say we all have our own opinions and choices and if one helmet to another helmet will save our lives and then years ago that Moto1 rider had a accident his helmet rolled away from the crash to find his head still in it, it happens and is out of our hands, its the risk we all take when on our bikes.
It won't stop me wearing any of my helmets from one to the other each one has its prepose and use, one better than the other and is a $800 helmet going to be better than say a $400 helmet its getting the right one that fits as everyone is different in head shape and size.
Remember the old days of heavy helmets, the old Bell full face helmets for one, but then only us old buggers will remember them.
Ashley