I tried the BingItOn.com challenge: 5/5 for Google for me. But I saw that Microsoft was trying to push me towards "popular" queries (what Miley Cyrus said today about the government shutdown). So I think this is an issue of demographics and sampling: for mass-market 'leisure' queries I could easily see Bing beating Google if that's what Bing is focusing on.

Equally, using Mechanical Turk is probably a biased sample (although to their credit, the paper does examine the demographics in detail); mechanical turk workers are paid more the faster they can find results, i.e. they are top-result driven, whereas I would guess leisure queries are more focused on entertainment and finding something interesting in the first few results.

And (despite the fact that I went 100% Google), I figured I should probably be using something more tech-focused, based on my queries, like DuckDuckGo. From that point of view, I think this BingItOn challenge delivers on the goal of getting people to re-examine their preconceived notions of which search engine they should be using.