I like your point about the ferrous reactivity; I wonder what the byproduct of the metal breakdown is. FeSO4 + C17H37NO4S = ? and then the SS reaction = ? Anyone feel like doing some reactant/reagent redux work at midnight......because this guy doesn't. At quick glance i'm going to guess we're looking at some carbon di or mon oxide gas, sulfur gas, and dissolved iron.
All chem BS aside my main thought was that it scores a zero on reactivity, so you'd think it would be safe on most metals, even the Chromium in the steel & NiChrome. After doing some reading i've found conflicting results. The CLR company claims it works wonderfully on SS, Al, and Cr (Q = "Can I use CLR Metal Clear to polish my automobile hubcaps? A = Yes. CLR Metal Clear does a great job of cleaning chrome, stainless steel and aluminum hubcaps and wheels."); but then i've read that it looks wonderful at first, then changes to rust the next day. Check
this out though, pretty impressive if you ask me.
Anyways, i'm putting way too much work into this and I think you and I should just try it. I've got the CLR and will soon enough have some dirty atomizers. If you beat me to it that's cool too. Please let me know, great chatting chem with you; it's been a while for me. I'm anxiously waiting to order my first e-cig (going with the Modern Vapor Sidesho) and i'll take a good long look at the atomizer on it. At $12.95/atomizer I totally understand your want to rejuvenate them.