Stability is integral to an enjoyable off-road experience. That's why truck owners and off-road enthusiasts will often spend hours talking about how good their shock absorbers are. You can only be as stable as the shocks on your truck allows for. The more rigid the shock absorbers, the greater their capacity to absorb the forces (vibrations and shocks) that characterize the off-road driving experience.
The amplitude and frequency of these forces is seldom predictable, and you might find yourself in an extreme off-road environment that proves challenging for your shock absorbers. Enter the suspension seat.
For the record, a suspension seat might not have much of an effect if the shocks on your truck are in bad shape. Suspension seats are designed to enhance your protection against the forces and vibrations mentioned above. They're not meant to be your primary source of protection from these forces, and you should not use them as an excuse to neglect your shock absorbers.
True to their name, these seats are designed with an internal suspension system. This system is charged with the responsibility of absorbing the extra forces that may bypass your shock absorbers before the forces are transferred to occupants of the vehicle. For this reason, a suspension seat will afford you an off-road experience that's less wobbly.
Even with the best of shock absorbers, external forces could easily reach truck occupants if the terrain is sufficiently rugged.
The Suspension System
Suspension seats are either mechanical or pneumatic. Mechanical seats rely on coil springs to provide the shock-absorbing effect, while the same effect is achieved using air pressure in a pneumatic suspension seat. You're likely to spend more on the purchase and installation of pneumatic suspension seats. The extra cost is justified in various ways.
For example, the degree of shock resistance provided by a mechanical seat fluctuates as its coil springs continue to get displaced. A pneumatic suspension seat provides uniform resistance against the wayward vibrations and shocks. Because air pressure on these seats can be adjusted quite easily, it's possible to increase your level of protection as the terrain continues to get more rugged.
Should all the seats on your truck be suspension seats? While not mandatory, this is advisable. The driver needs to be stable enough to steer the truck safely over rugged terrain. Passengers need to be protected against the potential dangers associated with riding on rough terrain (e.g., back pains).