I don’t like using the gun bearer in the dark with a headlight due to the distracting shadow created by the barrel. I was on some narrow trails a couple of weeks ago and the effect almost caused a misstep or two in some places I would rather not be misstepping.
Also, for me, the gun bearer is best with a sub-8# rifle. But, I acknowledge that I am kind of a wimp. I do like the gun bearer in the daylight with lighter rifles.
I also attached a second upper strap to my frame so I could use it like the SG system when I was not needing as quick of access to my rifle.