You are absolutely right about your scenario being worse than mine 😛 But as you said that is a hardware issue which is outside of my control quite frankly. When it comes down to it people buy devices like that Rain Bird not for the hardware but for the software preloaded. We can absolutely do the same thing and probably better just need some information.
It sounds like you have the right metrics in mind and a good end goal metric however I have zero time to research. Again, if anyone can bring me the information I would be glad to incorporate it!