I would be, at least for ad networks based in the United States or Europe. The rhetoric around online privacy has gotten rather heated lately, and they're trying to avoid government regulation by being on their best behavior and trying to self-regulate. Evercookies are the opposite of that - it'd be like holding up a sign saying 'make me a target'.

Back when things were a little less heated (aka a couple of years ago), some companies did use a combination of cookies and Local Shared Objects in order to provide redundancy - information deleted from one was later restored by the other. Those companies have almost certainly stopped.

Not that it indicates any wrongdoing, because there's a class-action lawsuit for everything remotely advertising-related, but there's been a ton of class-action lawsuits in the Flash cookie space. I believe the ones involving actively rewriting deleted information have largely been settled, and now it's mostly lawyers trolling companies for the use of Flash cookies to store any type of information more complicated than a volume setting.

For a recent example, search for Del Vecchio vs Amazon.