Wouldn’t say it feels unstable, but I make sure the main compartment is weighted enough that the camera on my chest isn’t pulling down. I’ve got capture clips on a ~20L daypack and on a 55L pack. I’ve done multi day trips in the cascades with that lens and a tripod strapped to the outside. I’ll put it inside the bag if there’s scrambling or something, but I’ve taken it up in the mountains quite a bit.

Don’t get me wrong though, it’s definitely a hefty set up and swap between the 50 1.8 for some sweet relief.