I'm right-handed, but left-eye dominant (wierd as hell). On a Rifle (Scope or iron sigts) i use my right eye, but for handguns, i use my left-eye. If needs be, i will switch hands without too much problem, both with rifle and handgun. Its mostly a challenge in difficult position with a Scoped rifle (sniper), but still doable. So i'd say i'm 100%/50%.
As a side note, i'm an instinctive shooter; meaning i don't often 'look down' the barrel for long. I'll point and shoot mostly on reflex based on experience of BB trajectory. Anyone else do that? I guess it takes practice, but for Airsoft, sighting is sort of a waste of time in my opinion, unless using a long scope of some kind.