I bought my 3500 with a 5th wheel in mind, but pulled my 7,000 lb TT with it for a few months. Weight distribution was not needed, so I pulled with out it for a bit. I had never had issues with sway, but the trailer did move around a bit on some roads. I also noticed that on those same roads with frost heaves in places, there was a bit of porpoising, although nothing bad.
I set up my Equalizer with 4 point sway control, and the difference was definitely noticeable.
The step up from half ton to 3500 was a huge step up re towing experience, and the WDH with sway control was another step up. For the few minutes it took to hook up, The payback was worth it for me. I used it every time the trailer hit the road.
Sway can sneak up on you, and it's good to be proactive in my mind. You never need it until you do.