> To string does exactly that, and will also remember null vs. undefined. So String'ing it is actually more stringent than that you are suggesting.

I get that; but such speficity does not extend to anything more than primitive data types, hence why you wrote "not 100% accurate". Simply marking the presence establishes what exactly we are comparing.

I have neither a very strong view nor argument here though, just putting my opinion out here. If you still feel that you prefer the string conversion, by all means please go ahead. :)