Does "$0" convert better than "free"?

Last year, Korean researchers found that people were more likely to choose a "Get it for $0" offer compared to when the same offer said: "Get it for free".

They tried it in 10 different experiments and it worked each time.

I've started using "at no cost" for my free newsletter, which is supposed to have the same effect, but I don't have enough data to tell whether it works or not (and anyway it wouldn't make much of a difference at the early stage I'm in).

Have any of you A/B tested using "$0" instead of "free" before?

Really curious to know if it actually works in practice as it's supposed to.

Here's the research paper (and here's a 3min summary I wrote about it)