I had them on my Palomino and loved the way they felt while towing. Mine was only 12 years old when I sold it so I never had an issue and can't speak for longevity past that. If you feel the trailer is too low, you need to remove the axle and place a block (2"x2" tube or solid stock) between the axle bracket and the frame rail...not a huge project for the right person or shop.
Edit: The more I thought about it...I realize that I had the AL-KO version of that type of rubber/torsion axles on mine. The concept is pretty much the same but with 3 pieces of rubber instead of 4.