Reading between the lines it sounds like they are only using their own crawlers and other partners for things like widgets, while all their regular search results are still just Bing.

I was going to say that if the two search engines index and rank in a similar way, you would expect the search to be similar. But, for the `uefi hack` search, the results really are pretty close to identical, and when I do the same search on Kagi and Google, I get different results. I still don't know if it proves anything, but it's a little suspicious.