I really like the idea of silicone muffin pans - no paper needed, and no exposure to the chemicals found in non-stick metals. I've only used these once, and while they worked great, I question their durability and safety. I have two pans, and several of the silicone cups in both started to detach from the metal while in the oven. I was able to push most of them back in place but a couple refuse to go back on. The silicone itself appears to have warped slightly, which also makes me wonder if they're truly food-safe, since silicone is supposed to be impervious to heat (at least at normal oven temps). I'll still use these occasionally when I really want muffins, but am going to stick mostly to glass loaf pans just to be safe.