I have to second Dusty's experience. I installed Teflon "E-Z Glide" liner strips between each spring leaf after cleaning and painting the leaves with POR-15. Results were a much improved ride and no "lively" behavior, and no apparent loss of load capacity. NAPA gas shocks were installed at the same time.
I'm not sure a spring shop would be an unbiased source on this. They don't make any money by advising customers to install their own backyard solutions.
