Helmets are a must!!
It is understandable that due to the very nature of the multi-role usage we find ourselves in nowadays: one minute slinging a dirty drill and the next flying tourists around looking at views or fishing, the question of helmet or not to helmet could merley be down to a perception of those being carried.
Ultimatley it is down to the individual and perhaps the operator/manager prefrence concerning a particular role. My position is wearing a helmet what ever the role!! I stand no greater risk from becoming incapacited due to a bird strike during corporate roles than I do from sling. Plus as I spend the most time in the driver's seat, I guess statistically I am at a higher risk of a injury.
It is wholly personal, I advocate wearing them always. I have a Gentex but see the Galet range has come on leaps and bounds.