The bags significantly improve the ride quality under tow weight. They supplement the springs and soften the ride which means more controllability of the vehicle which is important to me when towing. They also aid in leveling which helps with weight distribution which is really important when towing. If you’ve ever towed a trailer down an interstate like I-95 at 60 - 70 mph where the road surface is bad/under construction, undulating and uneven causing bucking/porpoising and a tractor trailer blows your doors off it’ll make you appreciate the extra stability I feel it adds.
I use a Curt BetterWeigh device every time I hook up our bumper pull travel trailer which is heavy. The device measures tongue weight, and weight distribution among all the other things it does. The tongue weight on our TT is around 1300 - 1500 lbs fully loaded, the trailer weighs up to 11k lbs total. The truck squats pretty hard but the weight distribution hitch (WDH) levels it out. After hooking up the WDH I use the Curt app to measure the transfer of weight when I inflate the bags to make sure I’m where I should be. The bags will significantly shift weight off the tongue and rear axle to the front axle making for more precise and correct weight distribution. My previous 2500 Limited had the factory air which worked on magic, it just did its thing all by itself but I didn’t have any input or control over it. The Air Lift set offers me some degree of control by allowing manual input. I‘ve towed with and without the bags and in my opinion, factory or aftermarket, they are worth the money for what I’m looking to accomplish. Good luck with your decision.