It's all very confusing but what I read says that Quintana Roo will not adjust for DST.
I translated this newspaper web:
http://www.sipse.com/novedades/hoy-c...oo-135195.html
It says
In April, when the rest of the country Daylight Savings applies, in Quintana Roo does not make that adjustment , so will the same time that institutions of central Mexico .
"The rest of the country will change and we will remain the same, will now begin a study and analysis of the benefits that will bring the new schedule to the state," noted Cristina Núñez Alcayaga, businesswoman who has taken the baton of schedule change from term as president of the Business Coordinating Council (CCE).
It doesn't make sense to me if they were trying to grab tourists from the Eastern US, why would they not want the time to match for more than half the year?