Not trying to start up the catch can discussion again but I found an interesting bit of information regarding the 2018 Ecoboost engine changes.
If I am reading the info correctly it appears that for is adding port fuel injection to the DI on the new motors. Maybe the do realize a carbon build up problem with the motors.

 

All the engines in the 2018+ f150 will be dual port&direct injection.

The horsepower numbers have been released except for the diesel engine.

 

This is why I eyed the Eco but picked the 5.0L because I needed to buy the 2016. I was also tracking the Tacoma at the time, and seeing that Toyota went with the dual injection system too, I personally thought that DI-only might cause issues down the road.
Do we know if the GM 5.3L (DI) is having carbon build-up issues yet?

 

Carbon build up doesn't seem to be a common problem on the 3.5 Eco. If it was there would be several complaints in the 09-14 forum.