I looked into those b4 I decided to get a full suspension lift with new springs all around. The one thing I was after was more weight capacity with a lift. with zero rate you dont get that. If your springs are worn, they will still be worn and saggy with a zero rate. I think moving the axles is a benefit and is probably why alot of ppl do that. If I was on a budget, id go with shackle flip b4 zero rates.