MC here,
I operate a Cessna 172 for aerial mapping and have dipped my toe into UAV's and I'm not seeing any advantages in these machines in our field yet. They will crash ,on average, 3 times a year. Even the expensive ones, they have no redundancy and parts are hobby grade. Their not allowed over populous areas (because they cash 3 times a year?) and the coverage per hour is too low to make a decent buck.
The Yamaha ag copter can't carry enough chemicals etc to be viable yet.
Having said that ,I lost a friend just lately to an ag incident, I guess with the Yamaha , everyone comes home to their family that day if it crashes.