Well I am not so sure that is a benefit of GDI (Gasoline direct injection) the main benefit of GDI is increased fuel efficiency, since you are wasting very little fuel and you can also run leaner. The biggest problem with traditional fuel injection is you can really only inject fuel efficiently when the intake valves are open enough to get the fuel in the chamber. The timing of the valves and injectors are not as precise and you end up with a less than perfect atomization of fuel on the closed valve at the beginning and end of the intake cycle. With GDI you have the injector sitting in the combustion chamber and it can spray fuel at anytime including the end of the exhaust cycle.
So while you could not get the same fuel mileage out of the 3.5L Ecoboost with port injection you could make the same power at the same RPM's just at the sacrifice of MPG.
One of the downsides that many people are finding with the GDI engines is that without fuel being sprayed on the back of the intake valves they are getting terrible deposits which limit air flow and cause sealing issues. (One of the reasons you hear fuels claim they have detergents added). SO many manufactures are doing both port and GDI.
This is a picture from F150ecoboost.net what shows the Ecoboost valves.