What is it about the XE (CC 4x4) that makes it have a lower towing capacity (6,500 lbs vs 7,400 lbs) and GCWR (11,800 lbs vs 13,000 lbs) than an SE? Tire load rating? Also, if I did get an SE with Big Tow is it just the lower gear ratio or are there some suspension differences too that increase towing capacity to 9,400 lbs? Since the Big Tow only comes with a Class IV hitch, do you really have 9,400 lbs. with it or do you have to use a wt. distributing hitch? Thanks!