I have been wondering about this as well and I have a couple more questions.
I don’t currently have the rain sensors or other weather sensors but I would eventually like to get them and add them to my system.
Are there DC versions of the AC sensors available? Can they be used with OpenSprinkler(DC)?
Am I giving up anything (other than the 24 volt AC sensors mentioned above) by going with the DC version?
In other words, other than the AC Sensors, is there any advantage to the OpenSprinkler(AC) that seems relevant?