I put RPI Designs stealth guards on the front and haven't gotten any chips on the gilles in the 2K miles since installation. And yes I have looked VERY closely so I'd have noticed if I did since I'm beyond anal about the car. I have XPEL film behind the rears since I didn't like the look of the rear guards... so far, so good
So they work or I'm just really lucky. Either way, I've got no complaints.