Yes, I do use these.
The ones I use are metal, though the ABS Plastic ones are really durable and the owner of the company, Rob, plays with those on his kit. Plus they are less expensive than the metal ones.
New designs are in the works, I have seen the prototype for the skeleton hands, and those are BAD ASS!! Rob said he is sending me an email with some more designes, but I don't think I can share them until they are in production.
It's a cool way to pimp out our kit. I get compliments all the time about how sweet they are.