If you ever had a trailer push you down hill, you would not want to do it again.
But then, pretty sure you already knew that.
As a teenager I worked summers for a local farmer in England.
One job was hauling grain from the field to the driers/storage. I was told that I should NEVER take the tractor out of low ratio when going downhill on public roads.
Well of course I had to try it

The feeling of 10 tons of corn being sucked downhill by gravity is something I will never forget. Luckily the road flattened out, no bend.