I have a few that I bought on clearance from Home Depot quite a long time ago. They seem to work fine, with very little delay. In that same kit was a GoControl Z-Wave Motion Sensor which is somewhat slow to respond, and not great for lighting automations. But the contact sensor seems fine. To be honest, almost all of my contact sensors are hard wired into an Arduino running my HubDuino software. So, while I have a few GoControl contact sensors, I don't use them for anything critical.
You may want to ask @jd1 as he appears to be using them.
