I’ve got a few of each. The FL has a more durable and thicker stretch material. It has a somewhat slick feel and because of that it doesn’t get a good bite - flip side it’s easier to adjust. Has a traditional pass through buckle and a plastic clip on the end piece.
I far prefer the Marsupial though. While I don’t think it will last as long, it’s low profile design is damn near perfect. Clips on very easily and you never know the buckle is even there.
FL on top, Marsupial Wolf grey on bottom. You can see the difference the texture.