Sure, people lie, when they feel they need/want to. And presumably that's an issue with any self-reported behaviour, including the Marie Claire survey. People can lie in either direction: claiming they watch porn when they don't, or claiming they don't watch porn when they do. I like to think that the people I work with have no particular reason to lie, partly because of the reasons they give for not watching porn. But I can't know any more about my sample than any other researcher who relies on self-reporting.
As for feminist porn, I think SaucyJack has a point, and yes, paying for porn is an issue, especially when specialist (eg feminist) porn is probably more expensive to produce. I don't think the idea of feminist porn is particularly surprising; it's really not just a matter of a man asking a women for sex (I'd like to think it might involve a woman asking a man for sex, but maybe I'm hopelessly idealistic...)
At the behest of my therapist I watched some porn produced by a woman porn director. It wasn't feminist porn.