I am a huge fan of Cliffy's product, service and dedication to the hobby.
The only issues I've had with Cliffy's protectors have been on games with clear coated playfields.
My IJ williams had crazy airballs when I installed the protector on the center ball lock shot.
My MM had some bad hangups/airballs when I installed the drawbridge protector. Do I regret buying either of these? Hell no. If the machines ever show real wear then they're going right back on.