When it was time to spec the seats for my Solstice a memory from my youth made the decision easy. The family business was an auto upholstery shop. About every 3 month a different roadster with leather seats would come in with the stitching pulled completely pulled out ot the leather upholstery. Seems that if you left your car out in the rain and the seats got wet they would shrink and pull out the sticthing. That was 1960's british roadsters and they used cotton thread and I have no idea of the leather tanning process in use at the time but I ordered the cloth for mine. Hopefully this info will be useful to someone else and just maybe help save someone from leaving the top down during a rain storm.