I have larger chunks (1-1.5 cm) of cc and shell mix 1" thick.
Pros: great for pods to hide in; easy to vacuum; has been easier to care for than 1" sand; does not blow around much in current.
Cons: traps debris so you have to vacuum; eventually gets covered in coralline algae, which while in some circumstances desirable not as pleasing to my eye as crisp, white sand.