An interesting set of questions, Lennart! Let me first explain why I am looking for reliable sources on the Gendergap. I have been involved with efforts to reduce the Gendergap in the Netherlands since 2011. Our big news today is that we have nearly doubled female participation from 6% (measured in 2013) to 11% according to our latest survey results from this year. One of the problems I have in discussions regarding the Gendergap is the whole chicken-and-egg theory about whether women don't participate because of a lack of female-related content, or whether we lack female-related content because we have so few female participants. It would be nice to have an article in the Dutch Wikipedia on the Gendergap to answer these questions without repeating myself constantly, but I see that so far since publication of that article on the English Wikipedia on 30 April 2014 (called "Gender Bias on Wikipedia" in order to differentiate it from the "Gender Pay Gap"), only the Turkish Wikipedia has managed to create an article in their wiki on the same subject.
I would really like to make an article in the Dutch Wikipedia about this, and in this context we would rely on Dutch "reliable sources" but what they have published so far is quite thin and only refers to the English Wikipedia, which is not helpful. Slate is not recognized as a reliable source by the Dutch Wikipedia, and this article, though interesting, does not touch on the participation gap in the Netherlands or indeed why it even matters. The Slate article is focused on an edit-war which is not really relevant to the larger community because as you say, though the language on talk pages in nlwiki can be very condescending or negative, it's generally not profane like this one. I do think from conversations I have had and research done by Aaron Halfaker and others, that the problem stems from the strange need to throw links to help pages at newbies rather than talk to them normally in language they can understand. Some of the very worst articles in the Wikiverse are help pages, which are probably bad because they are not indexed by Google and have too few eyes looking at them. That said, the help pages need a better "between the lines" analysis for the AfD queue, so that Dutch abbreviations like "Vrouw-baan" on the Dutch AfD list are interpreted correctly to mean "This editor is probably a woman promoting her own business and COI policy applies here" rather than what it sounds like "all women who work should have their articles be deleted on eye contact". I have also noticed that articles about women tend to be nominated much more often for deletion than articles by men. Ditto the books they write, the movies they make, and any notable news items they are the subject of. I think women give up quicker because they are less tech-savvy at finding their way around the various bits of behind-the-scenes discussion areas. Often they can't even find their way to the discussion at the AfD queue or the Village pump.
Why doesn't the Swedish Wikipedia have an article about the Gendergap? What is the Gendergap in Sweden today?