100's is not thread count but references the diameter of the yarns used to weave the cloth. It is related to the micron count measurement of the size of the threads.
Quality supers are just as durable as any other cloth but there are many variables to make a cloth of quality. Not all cloths are created equal.
Discussion of cloth/wool quality - not just the diameter but also the benefits of length, strength, crimp and luster.
About 1/2 my coats are made from HL, but I'm not sure if Samuelsohn uses them. Holland&Sherry is more commonly distributed and the Crispaire is a great travel cloth.