The question in... question, is mine:
It was put on hold as primarily opinion-based. I don't believe this is the case, the question confidently satisfies almost every single one of the guidelines on constructive subjective questions in the Help Center:
I made it clear several times within the question that I was primarily looking for answers that cite empirical tests and data.
As I see it, there are a few possibilities here:
a) That data exists out there somewhere and hasn't yet been brought to popular attention. In this case, it'd be a massive shame to have closed the question prematurely as that's exactly the kind of content SU thrives on.
b) That data doesn't currently exist because no-one's yet conducted such tests or published such papers. In this case, it's still worth keeping the question open to allow it to attract such answers from future browsers of the site/search engine visitors, as its existence may be the catalyst for someone conducting those tests themselves. Closing it just because no-one can currently offer that data seems unfair and counter-productive.
c) The worst case scenario, where that data hasn't yet been conducted and never will be. Even in this scenario, the site's users are still able to respond to this question with their own experiences, and in the absence of empirical evidence, expert anecdotal evidence is the next best thing. These are experiences, not opinions, meaning they fall well into SU's scope of constructive subjective questions above.
Based on all of the above, I believe keeping the question open is of far more value to SU than closing it. Thanks.