[PPCGeeks4ME]

In Settings -> Wireless & networks -> Mobile networks there is an option called "Enable always-on mobile data." I've seen several sites recommend turning this off, with accounts of it doubling battery life in low-signal areas. When you turn the option off, Android warns you that some auto-updating data applications won't work correctly, but I've seen many reports that this is not the case - Gmail, FB, and other apps still update fine with the option turned off.

Before I disable it, does anyone know exactly what this option does? I can only think that if turning this off really can double your battery life without reducing functionality at all, it would be turned off by default. There must be some negative to having it off. So what is the tradeoff?