I haven't seen any mention of this here, but Eastlan, a ratings service that previously measured only smaller markets, has been covering some larger markets including Atlanta for several months.
Eastlan reports all stations meeting minimum requirements, including non-subscribers, which means Cumulus stations appear in the reports. The reported shares for Atlanta are for Persons 12+ rather than 6+ shown in Nielsen reports for the market.
You can see the numbers at Radio Insight but looking at them quickly, I didn't see much of a difference from Nielsen.
Eastlan reports all stations meeting minimum requirements, including non-subscribers, which means Cumulus stations appear in the reports. The reported shares for Atlanta are for Persons 12+ rather than 6+ shown in Nielsen reports for the market.
You can see the numbers at Radio Insight but looking at them quickly, I didn't see much of a difference from Nielsen.