Personally I do not mind that course bearing has a little delay. If this helps to save battery then all is well. Actually, if it was to be computed every
two seconds that would be just as fine. Concerning the hardware compass, I am using "heavy filter" setting to make it less twitchy. With a compass line this gets even more important so the line do not go "all over the place". Maybe a "ultra, ultra heavy filter" could be used?

Perhaps even remove the filter option entirely and make a VERY strong filter default? Unless battery is affected from heavy filters...
As for colors:
-Course bearing. Red is already perfect. Highly visible for topo, seacharts and photos. Also when the sun shines on the screen. Highly visible in night modus too. Vital text for movement is speed and degrees.
-Compass line. Orange for high visibility just as the "show view" bracket? Vital text is just degrees. As for the arrows...Hmm, are they needed at all? This will make it stand out from other lines and also reduce screen clutter.
I guess pressing the compass button in the GPS-screen will turn the line on/off -and equally so for "use hardware compass"?