Well, first off, you don't smoke anything in an atomizer, you vape it. If you get smoke, you're doing it wrong.
Secondly... it's irrelevant to post some abstract figure, because everyone is different. The question should be, what nic level in an RDA is right FOR ME? Could be anything from 1 to 50mg -- I knew someone over at ECF who vaped 50mg in an RDA. (BeckDG)
Don't concern yourself with what is right for other people -- worry only about what is right FOR YOU, because that's the only level that matters. I went from an RTA (Kayfun) to an RDA (Achilles) last year, and dropped only 1mg, and I only did that because the RDA had a better throat hit. If you find yourself twitchy, nervous, nauseous, or headachy after going to an RDA, then the level is too high and should be lowered... but don't get crazy; drop it 1 or 2mg and see how that does.
Andria