The service itself is also kind of expensive for the chance that you might be able to get a cheaper flight. I plugged in the data for an upcoming international flight path I need to make soon and the total was $85 for service, which is a bit in my opinion for the chance that the service might be able to find a cheaper flight plan.
And since it's non-refundable unless you can prove there is a cheaper option, it's sunk money if there's nothing significantly better. I'm honestly not sure how much stronger this is than just using the multi-flight tool on ITA Matrix in a lot of cases, especially since the secret is basically they'll hunt for the hidden city flights, which with a small bit of research you can do yourself.
Article says:
...but what if they don't find anything? Fair question. It's possible you've already found the cheapest rate you're going to get. Flystein has a beat-my-price option where you only get charged if Flystein actually saves you more than their fees.
And since it's non-refundable unless you can prove there is a cheaper option, it's sunk money if there's nothing significantly better. I'm honestly not sure how much stronger this is than just using the multi-flight tool on ITA Matrix in a lot of cases, especially since the secret is basically they'll hunt for the hidden city flights, which with a small bit of research you can do yourself.