The 3rd party "Hunter Hydrawise water meter", not just flow sensor, is <$90 (3/4") $100 (1") street price and should be a far better option than the far more expensive 3rd party flow sensors currently recommended for the Gen2 Rachio.
Are there any plans to integrate an actual water meter into the Rachio Gen2?
Cash flow & time are both tight, I purchased the Rachio Gen2, bypassing Gen1:
(1) partly because of inadequate research
(I generally strongly the Hunter irrigation products, had missed the Hunter HC-1200i, yet, in retrospect, wanted more zones for future flexibility (currently using only 6) & did not really need the LCD display)
(2) was wary of the Hunter charges for web access in which the no charge plans severely limits both weather integration and the number of users.