I have a Ken Null SKR holster for a Colt Detective Special, which shares some of the advantages of the SMZ.
The upside-down positioning hides the gun very well, and provides for an exceptionally fast draw for both the strong hand and the weak hand, although the muzzle will cross your own abdomen for the weak hand draw. I don't know if the SMZ provides the same weak-hand draw advantages.
The plastic is durable, thin, and not harmed by moisture. It is a very good holster material. It is softer than your gun's metal and will not scratch your gun. The white color will not show through a white concealment garment.
The harness is the weak point. I find that it applies too much pressure to the back of my neck. I cut my harness off and replaced it with a modified figure-8 style harness.
Ken is good to deal with.