I know three people with the 2.7. Two older ones and a newer one. They all report great fuel economy and no problems.
Ford does have a blurb in the manual about using premium "for best performance" but nobody that I know uses premium and they still love the performance. I use the cheapest fuel that I can find in both of my 3.5s with no issues and plenty of performance even while doing serious trailer pulling. A lot of modern engines can adapt to fuel octane and contain similar advice for best performance but still don't require premium.
The 3.5 high perfomance found in the Raptor and Limited do require premium but they are the only ecoboost engines that do.
