How does polyester and silnylon compare head-to-head in terms of stretch/sag, water absorption, abrasion resistance, UV resistance, etc.?

I’ve been a collector of Blades since before my teens, and a retailer coming up on 15… or maybe 20 years. Drop has really been kind of an interesting experience for me, because I do occasionally get to see some unusual tech and sometimes EDC items that otherwise I might not have been aware of. And maybe it’s because I have a deep love of cutlery and bladed weapons, but I find myself trolling through the site looking at it what’s available; and it’s just it’s pretty much the same. And the bladed community here is just always confused me.. every single knife is about the same, they’re almost all drop points and although the handle materials change and brands change.. it’s really just the same knife over and over and over again... occasionally you’ll see a tanto or a slight variant; but rarely… and almost never a serrated blade. And I’m just deeply amazed at this diversion of serrated blades. And I’m just surprised there isn’t more of a request for diversity here.... and I...

And this isn't either of them! The Pandas we're talking about here, are watches, not bears. And what got me thinking about them (again) was a link posted this morning by @cm.rook who pointed a few of us to the very attractive (and not terribly priced) Yema "Rallygraph" Panda which, in it's most traditional arrangement, looks like the one on the left, but can also be had in the version on the right: The model on the left is a true Panda, while the model on the right is called a reverse Panda. The reason for that distinction is clear--Panda bears, only come in the first arrangement. Now at this point, everyone should be thinking about the most well-know Panda, The Rolex Panda, which is actually a Daytona, and among Rolex Daytonas, the most famous of which is the Paul Newman Daytona, which was famous first, because it was Paul's, and second because it sold at auction for $17.8 million (US Dollars). The story of that auction is well-known so I'll only...