Tex,
When your chain has stretched far enough to hook the sprocket teeth, you run a risk of actually loosing teeth from the CS, rear, or both. And yes, a chain can snap easier when elongated than if within spec. Not a very likely event under normal conditions, but a small rock could help with a quick demise.
No matter where you purchase your new set, be sure to practice good chain and sprocket maintenance and you will be happy with your set-up. Expensive is not always better. MFG's make some items extremly hard (and expensive) so they will last at least what you think they should with minimal care....however, cheaper items can last just as long, or longer, if you take good care of them.