Well I can tell you for me, I am now on my 4th visit for this vibration issue and I have owned this truck for 18 days. It has had the vibration since the drive home and tomorrow will be the 6th day in the shop with no definitive solution. So 1/3 of the time I have owned the truck has been in the shop.
I am a fairly new convert to GM. I had a used Avalanche that I traded in for my wife's 2014 Acadia Denali. They weren't/aren't perfect, but have been great vehicles that I enjoyed. Which is why I bought this truck. It has been a miserable new vehicle experience.
Next visit under this problem will be a lemon law final visit. If I get to that point, it will be the last GM product I buy. Which is too bad, as my wife really likes the Acadia and has already started talking about replacing it with the new generation, and I have been a big proponent of the new GM product lines.
I just want them to take the truck back, whether through trade assist or buyback, and I don't think that is unreasonable since the first visit for vibration was at 52 miles, 14 when I drove it off the lot and 19 miles home and back to the dealer the next day.