I completely understand where you are coming from and overall your solution sounds more robust. However, not all user’s will have dedicated syslog servers and typically want the device to work independently hence the focus on SD card logging. I think it should be fairly easy to change the logging method on the OSPi and possibly just add a secondary logging method with an option to switch between either or both solutions.
Side note though, I do have a Cacti server and would love to know if you are willing to share your scripts and templates for logging OpenSprinkler.
Thanks!