If it is a standard message I believe it should be supported. If not, we need it anyway.
If gps is the only data comming in, it is almost useless, however not completely, if the gps can give accurate velocity as well as position (not by derivative of position, but from doppler shift on signal) then it can also give a more accurate heading rate than difference from last two headings.
Most IMU (which is becoming standard instruments now) give absolute as well as rates for all 3 axes of rotation.
Eventually, I plan to write a raw-autopilot plugin to command arbitrary electric motor
configurations to steer the rudder
, trimtab, or control pendulum vane, rate of change is essential to implement a basic PID-loop, and gps rate of change derived purely from gps positions at 1hz does a poor job (I have tested on my prototype) So to work on only a gps, a more accurate message is important. I prefer magnetometer heading which is much faster, but a rate gyro would be even better.
Maybe one day we will have a plotting plugin that displays all the data as a sweep plot as well as can perform fourier transforms (make it easy to determine roll and pitch
period of vessel) and analyze performance in various sea states, calculate boat characteristics etc.. we need rate of change!