This would be very handy. We had pop-up storms here in Atlanta yesterday afternoon/evening, with my yard getting a thorough drenching around dinner time. Imagine my surprise when I awoke today to find that my flex schedules had watered one of my larger zones for 28 minutes (0.30 in) this morning. It appears that the nearest PWS didn't report any rainfall yesterday, which is entirely possible given the spotty nature of the storms yesterday.
I've thought about getting my own PWS to better capture the microclimate, but my yard is small (1/3 acre lot) & ringed with large trees, so proper siting for a PWS is between difficult & impossible. Putting one on the roof would likely run afoul of the HOA & my wife.
Another handy feature would be a single button in the app to "fill all zones". This could be used when you get a very thorough drenching, rather than going to each zone individually to fill. No rain gauge required.