I'm agree when you say that these trucks seem to be very sensitive to tire balance. According to the dealer: GM will replace a tire that needs more than 24 but these trucks needs to have a tires with less than 15. take it or leave it.
Based on my current open case and all the information here, tires should be the solution just for some of those trucks. There are various other problems that isolated and associate, creates the vibration. (drive shaft, read end, resonance in the exhaust, etc).
Looks like a very sensitive truck in general, humble customer opinion, they trying to get it lighter and lighter and this is the result... (Crew Cabs: GM: 5200lbs, F150:5600lbs, RAM: 5500lbs). So, when you have 500.000 "sensitive" trucks produced plus some quality control problem, statically we will find a lot with no problem, and a lot with different type of problems...