Stop Flats2 liners are a soft liner with a tough inner core. You can push a pin through the liner, but they'll cause resistance for road debris like glass (which has to puncture your tire) or thorns anyway. There is also shear stress from the torque and flexing as the tire deforms against the ground, rubbing the liner against the rim. This shear force tends to grind up bits of glass and thorn into dust, if it doesn't fully penetrate the liner.

After 450 miles I've yet to get a flat, despite riding over broken glass and pointy rusted metal. I assume I haven't encountered anything particularly fatal, more than that the tire liner is decent.

I bypassed the Slime liners because they're hard and prone to cause pinch flats. Everyone who reviews 'em online hates the damn things.

As Ziemas says, the Schwalbe are decent in the rain ... I have a set coming but haven't had the chance to put 'em on. Supremes are said to be fast and puncture-resistant; Plus are said to be extremely puncture resistant, but slow and heavy. Haven't decided if I want to transfer the Stop Flats2 liners to them or bypass the liner. Part of that is I don't want to bulge out the tire oddly, although the current Kenda tires haven't shown any indication that they're liner-equipped.