This is from Flex-Form's website, who makes after market composite springs:

 

They do not de-arch as they age as most steel leafs do. They do not corrode. And, the composite material has a compliance characteristic that steel does not have, allowing selection from a greater range of spring rates with vastly superior ride and handling characteristics. In most cases, our composite springs are priced lower than steel springs produced by the better-known manufacturers.

I recall paroozing through auto shows where composite springs were on display. I recall the composite mix (polyurethane support and other curing materials)  is very important and critical to a durable final product .   Environment (temperature, humidity, etc.) variables can have a huge impact of course, but today’s latest CAE and optimization tools can get you where you want to be with a robust design that offers a lot of benefits.

 

 

Huge fan of composite springs.

The next Silverado/Sierra could very well increase in size as the Colorado/Canyon are just a half step smaller.

 

Composite springs. Erm, I'd hesitate to use a Corvette example to demonstrate it's advantages for this application. A Corvette might get beaten around a track, but will it ever see the kind of rough and tumble some of these trucks actually see?

 I'd be very nervous about having composite leaf springs in a truck.

 

Why? Composite leaf springs are more durable than steel, they never rust, and they're "programmable" when they're built.    I would prefer a composite spring in a truck.

In some cases composites are vulnerable to structural failure due to seemingly superficial nicks and that kinda thing (ask any hockey fan whose seen a stick blow up during a slapshot attempt). Don't think it would happen here, but truck leafs are more exposed than a Corvette's.

 

composite leaf springs are famously used in the Corvette, but GM used them in a fairly substantial number of main stream cars too with no issues.

 

All of the first generation W-Body coupes had them (Lumina, Grand Prix, Cutlass, Regal) and a few of the H-Body 2-doors (Lesabre, 88) ... not sure about the 98, Electra, and Coupe Deville.

 

The composite spring is literally the only thing that won't go wrong in these cars.

I don't remember the source, but I do remember reading that Corvette composite leafs were the first item GM manufactured that was so durable that their Product Liability lawyers told them to stop trying to make them fail. I believe the originals were rated for over three MILLION full compression/rebound cycles before everyone just gave up and went home.