Of things i don't care for with my 2011 long box dually is getting longer. Today was a big one.. I can see the tail gate folding up like a pretzel.. It flexes a lot when i step on it I'm around 275lbs.. My 04 dodge tail gate has never flexed. I would be afraid to run my quad up into this truck on the tail gate like i do with the 04.. What gives. I thought these where work trucks. I like the cab size and the dually fenders being one piece.. as for the rest of it bah.. When i shift to second or third it feels like it falls flat on its face . Drop the pedal to the floor and it kinda speeds up... I'm buying ball joints tomorrow for my 04 and fixing it.. Sick of driving something that seems so gutless.

 

Not sure what you mean on the tailgate flexing or folding up. I am also 275-280 lbs and have loaded my triumph rocket(850 lbs) and my Honda Rune(825 lbs) with ramps on the tailgate and hasnt moved any. I have done it numerous times.
As for seeming gutless. Not sure if you have done any deletes or not, but until you remove the emissions to open it up it will seem like that. I did the deletes on mine and is a whole new truck. I also had an 04 and I believe the 4th Gen is a whole lot better in my book.

 

Step in the center of your tailgate.. Mine flexes close to 1/2 inch. The back bumper even flexes a lot...