I ended up going with the Herpstat 1 over the Intro+, but for the fact that it can accept a grounded plug should I need it in the future. Looking on the website, doesn't the Intro+ have the safety relay? Or is there an additional safety feature I'm missing?

On an unrelated note, Spyder Robotics is ON THE BALL with shipping. Ordered 2pm local time, and received tracking info within an hour - and will have my thermostat on Saturday!