I use my gpsmap together with my instinct 2x as a heart rate sensor, mainly for biking. This actually works well but there's an annoying and 100 % reproducible behavior/bug on the gpsmap:
As long as broadcast heart rate is active on the watch, it's impossible to permanently turn of the gpsmap. It turns off for maybe 10 seconds, then turns itself back on. Every single time you try it. This can be very annoying when you don't realize it happened and then find your gpsmap with a dead battery.
The workaround is, of course, to stop the broadcast on the watch or to forget the sensor/watch on the gpsmap. But it really shouldn't be necessary. Sometimes I just want to turn off the gpsmap and go on recording an activity on the watch without messing around with the settings.