According to Ford, in 2015 when they introduced the "aluminum F150" the use of aluminum reduced vehicle weight about 700 pounds, most of which was "invested in payload increases"... The truck frame and running gear was pretty much "left alone"...
In the "aluminum SuperDuty", there will be close to the same "weight reduction" with the aluminum body panels, but much of that weight savings is being "reinvested" in a heavier frame and some running gear modifications, so the payload won't increase as dramatically as we've seen in the F150 line. It looks to me from the limited reports I've seen, that Ford's payloads will only increase to be "somewhere close" to GM and Chrysler's current payload ratings.
Some reports indicate that Ford is "satisfied" with payload, towing capacity and performance, and felt the extra weight savings would be better served with reinvesting it in a "stronger vehicle"...
http://www.ford-trucks.com/articles/...mpaign=content
As for aluminum panels being "not as strong" or "more puncture prone", if you think about the skin of most aircraft that travel 500+ MPH through thunderstorms and rain/sleet/hail..... Good old "Mil Std .032" aluminum panels on the wings of fighter aircraft "manage to hold together" at 1200+ MPH. I wouldn't sell "military grade" aluminum short because of a competitor's advertisement...
Yup, I'm a Ford guy, so this is probably a "biased" comment, but hopefully not perceived as a "negative" comment toward any other vehicle brand.