I'm also a suspicious of the insulative coating fix. I think the proposed solution hinges on the idea that electrically isolating the hand from the conductive

I'm also a suspicious of the insulative coating fix. I think the proposed solution hinges on the idea that electrically isolating the hand from the conductive surface of the antenna would prevent it from loading/bridging the antenna. While a thin insulating layer would accomplish this at DC, it may not at higher frequencies, especially when you get up close to the GHz range. Your finger and the metal of the antenna are essentially two conductors separated by a thin insulator, which forms a capacitor. A capacitor blocks DC current, but its impedance (resistance) goes down as the frequency of the signal increases. What tesseract is suggesting is that the frequencies in the antenna are so high that our capacitor's resistance is practically nil; the thin insulator essentially does nothing to fix the problem. A possible way to fix this is by lowering the capacitance of our capacitor. The simplest way to do this is to simply increase the distance between the two conductors, i.e. move the finger farther from the antenna. If you look at Apple's bumper case, you'll notice that it is far thicker than any of the proposed insulating layers.