Thanks for taking part in the experiment!
I've read a few articles today, and just found another that support a close to 0 (but not quite!) payout on curation if you vote in the first 15 mins.
https://steemit.com/steemit/@vapekings14/the-truth-about-upvotes-curation-rewards-and-author-rewards
looking slightly better here as its reported that the scale goes up from 0 mins..
https://steemit.com/steem-help/@sykochica/answering-common-questions-about-voting-and-curation
I may adjust my text slightly :)
Cheers!