Here's an example of what I'm doing now using the capabilities of the current Gen 2 firmware:
Both obtained simply by monitoring the Rachio's pump terminals (total water usage) and the Zone 10 terminals (pool usage). Outside of the Rachio I'm subtracting Zone 10 from pump terminals to arrive at Sprinkler Usage.
Obviously I'm limited to reporting in terms of time (accumulation of hours of running). Still, on a 13 rolling month basis the feedback is useful to see progress being made saving water.
This is all Flex, with 10 zones total. I don't have any limitations configured, nor any default values overridden. Type of soil, slope, amount of shade are all accurately input. Plant Type is the only thing I've changed (buffalo grass = Trees, zoysia grass = Shrubs, St. Augustine grass = warm season grass, any zone with flowers = annual plant type).