I ran them for years. Really flexy springs. For the first few years, my rig was my daily driver. I had to get greasable bolts to get rid of the noise that the orbit eyes make, greasing them as needed.
Now, I am in the process of switching over to link suspension.
The guy who originally sold them, took forever to get them to you. I had to call the Grand Juction PD to go by his shop and find out WTF was going on, and had to threaten him with legal action to get them. Since the Alcan guys took over sales of them, I've had good experiences dealing with them when I had to get a new main leaf.