I have not used the ios compass app other than checking it at home, so good idea to compare it to Cachly. I'll give it a try tomorrow when I'm out and about. The compass app allows setting a target heading, so it will be interesting to observe how stable it is. I'll post what I find.
The fact that GPS "course" reading only reacts to device motion is exactly what is good about it! Compass mode has its use but so does this mode. I agree it should be off by default. Thanks for considering it!