Had to replace all 4 leaf springs this year. The old ones were not holding up the RV from hitting the bottom of the RV. I chose to upgrade the springs from 3500 Lb to 4000 Lb springs. Now I have enough clearance from the bottom of the RV to the top of the tires. I also notice that there is still a little arch in the spring even when I am fully loaded.
I have a small Winnebago class A with a huge slide of the passenger side and when I stood in front of my RV I could see noticeably that the left side tilted two or three inches. I took it to a truck place in Florida and I added a leaf spring which evened it up they gave me paperwork I submitted to Winnebago and got a full reimbursement! Leaf springs can be a good fix.
I carry a spare leaf spring as I have seen people post about them breaking. I have considered replacing them with 4,000 pound springs but they still have a pretty decent "smile" and we are within the axle ratings. One broken spring will probably convince me to replace them with 4,000 pound springs or do an independent suspension conversion.