Well alot of research has gone into this system, and i am working for a gm dealer. basically the engine cuts fuel to four of the cylinders, then it deactivates the lifters on those cylinders via an oil control solenoid. This allows the cylindrs to act as an air spring. And yes it is very sensitive and kicks back to 8 at the slightest load increase.
i have the yukon xl,,,i have over 3000 miles on it,2007,,,no problems ,,2000 miles are here in mexico,,,,,on high way it moves in and out ,,,helps on gas milage,,,here in mexico i am on dirt roads and rock roads 90 percent of the time ,,,,no problems so far,,,abuelito