The rear air ride on the 3500's is simply AWESOME!
I carry FULL RAWR of 9,750# when RV is attached. The top of bed is at 55" the same height as when it's unloaded in ALT trailer ride height.
There are two full length and two axle to front leaf springs. They are small in comparison to the regular sprung trucks and are there to hold axle in place and control axle wrap on launch. I have 40K on the truck with ZERO issues. I have NEVER heard of a single issue with this system. And you must not have been on here much for the last two years as I have posted on this topic MANY times. It's WELL worth the $1,300 option.