There have been various discussions here on DP regarding ccTLD's and ranking for things. Questions about .ca domain and .co.uk domains and such like. I have argued that some domains get special status and here is some News about this Seems .io is now one of those being given "special" treatment by the G's algo's. The list now includes > .ad .as .bz .cc .cd .co .dj .fm .gg .io .la .me .ms .nu .sc .sr .su .tv .tk .ws http://support.google.com/webmasters/bin/answer.py?hl=en&answer=1347922
i have had good luck ranking CCTLDs, and found that .ca and .io are easiest, depending on the niche and keywords you are targeting.