Thanks for your note.
My electronics are a B&G Vulcan plotter, Raymarine ST50 wind, speed, depth. They are integrated so the plotter can calculate true wind.
The courses we use are windward leeward. I have the marks programmed into the plotter and the plotter is displaying SOG, VMG, COG, DTW, TTW, BTW, and a bunch of other things. The Vulcan is designed for sailing and will display laylines, polars, etc.
I also have a garmin GPSMAP 78SC. It is not integrated to any instruments but does have waypoints in memory.
The Garmin and Vulcan both display VMG and it was very very close on both.
Since the course is windward leeward for the upwind leg I usually just trim the sails in as far as possible - headsail sheeted in until the leetch hits the shrouds, main in as far as possible, then traveler up to get boom on centerline, and then I steer to the tell tails.
I will do some research on velocity header target speeds.
How does your instrument system derive VMG? Is it VMG relative to true wind? Or to a waypoint? How sophisticated is your wind instrument?
IMO, you should be, first, picking your angles based on strategy and lay lines to the mark or destination, and then subsequently maximizing boat speed at that chosen angle.
In other words, “sail to target speeds”.
Figure out how to tell the difference between direction headers and velocity headers. How you drive and trim is different between the two.
Google “velocity header target speed” and “sailboat target speeds”