Attached is my Highlander on the runners harness with the runners kit bag. At the time of pixs, the kit bag hand cell phone small flash light bic lighter and just a large teck lok because I did not want to leave it lying around.
Attached to the highlander is a Camelback hot shot 3L, I have only tried it with about one L of water so far and minimal stuff in the highlander.
One pix is the compressed Highlander the other has 12 meals of mountain house food and a small pouched with miscellaneous items in it.
I have jogged up to six mile on multiple occasions with just the runners kit bag no issues, I have run at most three miles on many occasions with the kit bag attached to a tara pack using the runner harness no issues, stable comfy etc.
I have also run hills with the runner harness and tara no issue, stable.
Yesterday 1.5 miles with the runners kit bag on the runners harness attached to my highlander also attached is the hot shot. No issue other than me being out of shape and overweight. Surprisingly stable.
I dont see myself jogginf with full 3L and Highlander full attached to the kit runner bag, that whole set up would be more for a long day hike.
Overall the runners kit bag is slender but can hold a good amount of stuff and is very comfy.
I have had my Glock 34 in the back portion along with plenty of stuff in the front compact with no issues.