My understanding is that it's pretty common for performance cars with OEM suspension to run at or close to the bump stops. It allows them to run softer springs while controlling car motions at the extreme/increasing perceived roll stiffness as your data shows. I'd guess the dampers are tuned to handle this. I think the 1" drop case is not the end of the world because you're still staying within the range of spring rate the dampers were designed to run at low frequencies (basic chassis motion) - though on a bumpy (normal) track you'd be at a disadvantage especially in the corners/braking/accelerating and additionally wear out your tires slightly faster.
The 1.8"+ drop with OEM geometry/travel/bump seems silly though....