I've seen the sonoff devices, good devices and can be re-programmed so could be used as a pre-built controller with a few additions.
The sonoff SC is the unit that has the humidity/temperature sensors but they have opted to use the atmega328P (read Arduino) for adc to overcome the esp limitation.
There's a detailed look with modifications here:
Sonoff SC with MQTT and Domoticz support - Tinkerman
Also a guy called Peter Scargill has done lots with them
IOT Technology Blog
I'll post more details in a subsequent post.
Acuario