I’ve found that When comparing fabrics of the same weight:
Silnylon tends to be “tougher”, wears better and lasts longer. Does stretch when it gets wet, really noticeable with heavy wet snow. But for mostly fair weather camping, works great!
Silpoly, tends to be more fragile, Easy to poke holes in the fabric with branches and small twigs. Barely stretches at all, almost eliminates the need for “Cat cuts” and stays taunt throughout the night. It’s my choice for camping in wetter weather.
Silnylon tends to be “tougher”, wears better and lasts longer. Does stretch when it gets wet, really noticeable with heavy wet snow. But for mostly fair weather camping, works great!
Silpoly, tends to be more fragile, Easy to poke holes in the fabric with branches and small twigs. Barely stretches at all, almost eliminates the need for “Cat cuts” and stays taunt throughout the night. It’s my choice for camping in wetter weather.