I'm happy about the new "insource:" syntax, because every once in a while I find myself wishing for just that kind of low-level inspection (finding certain kinds of malformed information on commons file pages, for instance). Can I assume that the regex flavor is implemented in a way that's smart enough to only run it on files that would be the results returned by the rest of the query? I don't want to hammer the servers playing with it, but it did seem to be quite fast in my first use, which had a "prefix:" term that narrowed the field to ~600 hits by itself. Is this a reasonable usage?
Also, does the non-regex version basically just ignore non-word characters much like the other search functionallity? It seemed so from a few quick tests.
And, just to completely overload this post, I'm also wondering about what the "first paragraph" weighting would apply to in the context of a typical commons File: page... basically only up to the first heading? This could be significant in terms of best practices for adding information to the pages, I think. Current upload methods tend to slap a ==Summary== header at the very top of the page, while many older uploads are lacking this. Could this cause some wonky weighting of older vs. newer uploads?