Simple saddle pads/cloths are designed to keep the saddle clean and provide a bit of fashion. Other shock absorbing products work on a compression basis: when you apply weight or pressure they compress and at that moment they are not functional. As the weight is relieved non-compression foams release, or spring open. In the case of riding this effect actually moves the rider further from the horse. Gel moves away from pressure points, generates heat and shifts a great deal, reducing the stability and sense of security for both horse and rider.
ThinLine works when under the weight of a rider or saddle. Does not move and greatly reduces the feel of sudden impact allowing you to whisper to your horse with your seat.