Looks like the most recent trend is timing chains on high mile 2011's but has nothing to do with turbos or DI (unless it is a fuel in oil issue, but that doesn't seem to be a problem). Also appears that the replacement chain has more meat on it so not sure if/when that was implemented.
And about mileage, this truck gets better than any of the gutless 5.3 gm I've owned(3 of them) and weighs about 600 lb more. I also got a best of 25mpg(US gallons) on a flat stretch of road 70 miles long, sheltered in trees (no wind), staying at 60MPH or less. My 5.3's never saw numbers that good. If I stick to 60mph max, I can easily net 22 and have a range of almost 800 miles with the 36 gallon tank. Towing is better, too. So where's the problem? If you can't get good mileage in an ecoboost, you're not going to get it with any other remotely comparable truck except the new GM 5.3DI.