Sensordrone... I haz one :)
The sensors I have the ability to independently verify are pretty close, within a percent or two.
ambient temp, humidity, IR temp (I'm running a slight fever and it confirmed it), pressure, and altitude.
The others... no clue with no tools to verify at hand: illumination, precision gas (CO equivilent), proximity capacitance, internal battery voltage.
Haven't looked at any custom software yet. Just using the sonsordrone control app.