Hi, I was towing a 4 door wrangler (about 4600 lbs loaded) up until this year when I bought a 2024 Canyon Denali (about 4800lbs empty).
I do carry a bit of stuff in the bed so I am probably a bit over 5K lbs but have not weighed it yet.
It tows great!
At the same time as the toad upgrade I also added the 5 star tuner to my 2020, 2552.
With that I would say it pulls on hills as well or better than it did with the lighter Wrangler.
I have not had any issues with hills or braking with my Demco Sit in Play braking and Roadmaster Nighthawk Tow bar and base plates. (fun to install

)
The 5 star also made a big improvement in the shifting.
Here's a question for you:
When I found my hitch name plate it says it is rated for 5000lbs with a 500lb tongue weight -OR- 6000LB weight distributing.
Am I crazy to think that if it is good for 6000lbs weight distributing that it should also be good for 6000 lbs flat tow with zero tongue weight?
Thinking the Push/Pull forces would be similar whether Weight Distributed or Flat Towing.
Either way, I feel safe because I know there is a margin of safety built into those ratings and I am not over by much if at all.
It tows very well and I love the truck.