The Bighorn sil-cush padding is a rubber compound, they have only been out 5-6 years so no long term ideas on actual longevity.
Most people use what they call Fleece, but it is actually a synthetic and is the shortest lasting. Normally white in color, the thinnest of all choices.
The next grade is a HD synthetic fleece, orange in color.
The next grade is a part wool fleece with synthetic backing an orange color. Sometime called Faux-Wool or Faux Fleece.
The Best is 100% Wool Fleece, this is also an orange shade, but extremely expensive, for my money the faux fleece is the best.
The Sill-cush, imo is one of many gimmicks saddle maker use, why not use a Good Saddle Pad for the cushioning effect? Do not get me wrong, for the Money Bighorn has a few Models that are some of the Best off-the-shelf Saddles made today. Like the Voyager, Excursion and Infinity.
May all your Trails be happy and safe ones