I was all geared up to upgrade to the 6s, but the thread about the 6s cutting off by itself is giving me some pause. I recognize that problems get more forum attention than problem-free phones do, but this seems like a real issue. For what it's worth, I'm upgrading from a four-year-old 4S. It's slow and the screen is small, but it works. Any thoughts? Whether you would go ahead and upgrade or wait, please explain why. Thanks much.