I am extremely happy to report that this does fix the problem. This was the only complaint I had with the vehicle. Now, it rides and sounds just like a Lexus. I'm convinced that the fix resulted in a more "buttery" ride at any speed (although it could just be me). I had a smile on my face while driving home from the dealer...no noise at all. Ahhhhh...
The service department said that all new GX-470s are being delivered with this "fix" from the factory, so this shouldn't be a problem for the most recent vehicles...and it certainly won't be a problem going forward.
If you've been waiting or wondering if this fix would make a difference, believe me...IT DOES.