Did you buy yet?
I have a Jayco 29X 4800lbs TW 825lbs arrow hitch pulling with a 2008 Subuurban 5.3 liter 4th with towing package LTD
I get great milage on the flats not so bad on moderate slopes but yes,on the steep grades it does labor. I always verify my brakes on both the truck and trailer before every trip because I know that I am very close to the limits of my truck . The Hensley Arrow stopped my fear of the sway issue . after all the trailer is longer and taller than the truck. But I am very happy with the over all performance of the suburban