TexGX,
When you went up the RTI ramp, your driver's side rear wheel was spinning (no traction)...therefore, in technicality, you have reached the limit of your suspension travel. And yes, your front bumper was touching the ramp. My bumper touched briefly on my way down because i went off course.

As can be seen in the pics, my front bumper had enough clearance.
I must say though, my GF was very impress with the GX470's interior...it made my interior look old and primitive!

Damn useless COMMAND crap! I am just glad that she did not get to ride in it...she may have jumped ship over to the cushy Lexus.
FYI, MB G55 AMG has stiffer springs. G55 has a horrible ride off-road due to their lack of compliance. This is well-known. That is why in 2005 with the G55K AMG, MB toned down the springs (similar to G500).
Does TruckTrend measure RTI?? I did not know that. I don't think FourWheeler compared the G55 AMG...did it???
As you can see from the pics, my travel up the RTI ramp was comparable to you. My rear driver's wheel spun at about the same spot as your GX470 KDSS. With lockers ON, it was a different matter.
Pictures are worth a million words.

Thai.