From a safety perspective, being able to view the ejection port with your peripheral vision, meaning your right eye can see into the ejection port. This becomes a non-advantage should your rifle KB, for whatever reason, bad ammo, etc. If something is coming out of an AR15 rifle, its usually the extractor + brass and flame out the ejection port. Rare, but not unknown rare. Much more dramatic to a leftie with a RH gun, than a RH shooter with one.
And rocks fall out of the sky sometimes but nobody advocates wearing a helmet full time to guard against that possibility.
It hits my ear muff from time to time and the brass gets deflected towards my face giving me some light cuts on my cheek. The Peltor Shotgunners are not big cans but I think I'll have to wear ear plugs instead.
Something is not right here. I have shot tens of thousands of rounds out of RH AR's and never been hit by a single piece of brass. I was looking at my 300 Whisper AR last night and its brass deflector has loads of copper on it but I have never been hit by anything.