Thanks, I think we will find that there are several ways in which people start editing Wikipedia, and that creating a new article is one route that has becoming increasingly problematic. Another way to identify these editors is from messages on their user talk page, as usually they will get a templated message when their article is tagged for deletion. The messages vary somewhat, in my view the ones for vandalism, attack pages and spam are usually accurate and I'm not greatly concerned if those editors leave. But many of the others are "good faith" potential contributors even if their first edits weren't necessarily ideal.
Our first focus is on namespace 0, hence we do not include Talk pages (yet), the reason is that way we keep close to stats.wikimedia.org. But I completely agree with you that the Talk pages contain a lot of valuable information on the experiences that new editors have. Personally, I think natural language analysis could be a promising road to take to uncover micro dynamics of editors joining / leaving.