Been wearing a chinese knockoff from amazon for about 8 months now. Actually it's showed less wear than the stock garmin one that the watch came with and functionally it's identical
I have also some of these straps (and even a cheap metall one) in use with my 5x without any problems.
How wearing the metal strap impacts optical HR? I am thinking about getting metal strap, but I am afraid that wearing the watch loosely will impact HR monitoring...