Can’t speak personally to the Sierras, but agree on the coast range, and imagine that would be true of any forested place with real topography. The steep hills would make for tons of roll overs, as well as make it very difficult to aim water accurately. Hard to do halfway up a hill.
On fourth thought I have figured this out, and it is brilliant.
This is not about public fire suppression, it is about ‘corporate fire suppression.’
Imagine 2-3 of these circling the campus of ‘xyg’ corp, LTD making sure the encroaching wildfire remains off worksite.
In a manicured environment these could be very effective.
Out ‘inna woods’ they would be a liability.
IMHO