So I recently go into sub ohm vaping and I love it. I'm currently vaping a dual coil at 0.7 ohms, with 100% VG 8mg liquid. Is lung hitting all the time on that safe? That's pretty much how I like to vape now.
Probably not, but I guess that depends upon your interpretation of the definition of 'safe'. Too many unknown variables for me to give any opinion, other than that.
On just the point of the lung-hitting, I can't direct-lung-hit any smoke or vapor without extreme discomfort, yet I can mouth-to-lung either just fine, so I'd have to go with the observation that it can be more irritating to the lungs. I'd guess that more heat, and probably more nicotine, hit your lungs when bypassing the mouth draw.
Most likely better than lung-hitting smoke, IMO.