@plainsane, I think you are ignoring the basic point that I and others have been trying to make. and that is that in the calculation that Rachio uses, the surface area factor is completely superfluous for a single point emitter system. Volume UNDERGROUND is not the same a surface area, as you point out later.
I think that you have unintentionally highlighted the ridiculousness of the Rachio expecting it’s customers to be experts in both botany and mathematics. While you may be trying to water an oak tree with a drip system (not terribly efficient, I think) most of us are watering single shrubs or small bushes, flowering annuals and that sort. Why would I put a drip ring on a yarrow or a rock rose? A single pressure compensating emitter should do just fine. I do appreciate your example but it really underscores how completely lacking in support for single point emitter systems Rachio’s software is. An inch/hour calculation would not change the situation.
Your last point hit mine on the head - Why spend $250 on Rachio’s broken promises and deaf ears when you could get a much less expensive system with actual support that works better and does what we want? I would hope that SOMEONE at Rachio is listening but I’m not holding my breath.
And just for the record, two of the gentlemen I talked to had doctorates - one in Horticultural Engineering - so I do trust what they say when it comes to plants and numbers. And I actually do like Pepsi much better than Coke. : )