Since June 2018 I changed to an OpenSprinkler 3.0 DC in order to use the Zimmerman method for calculating the garden watering. What I can say in regards to my weather controlled approach is that weather forecasts are very unreliable. There were some thunderstorm forecasted in April, May 2018, which causes my weather controlled OSBee sprinkler system to stop watering for consecutive days. This is not good as there was no rain at all in my area.
Zimmerman is by way the better method to use, as it relies mainly on stable data from the day before. If you like to have a weather controlled sprinkler system it is well worth to change to or to start with an OpenSprinkler 3.0.