No particular rules at this time.
I'm on my first system. It's a Wink Hub with Quirky+GE Tripper door/window sensors and a couple of GE Link Bulbs and a pair of Pivot Power Genius power strips.
I love tech and I own a home, but the reason I started looking into it seriously was because our garage door was left open a few nights, even though my wife swore she shut it. The Wink system logs open/close times on all of our doors and allows us to set custom notifications.
The Wink system is not for home security, it even says so on their site. It requires an Internet connection to do anything. So if your Internet is down, you won't be able to control lights or be notified of events. This isn't really a problem for me as I have a reliable connection and don't use it for security (I now use a reputable security vendor for that).
It has been unreliable at times but all-in-all it's been fun and proven useful.