I got the original, full-sized Koala when they first came out also
I love mine. I thought they were a little big at first and I tried a couple of other different chest packs since I got the first one.
Now I am back to the original, full-sized Koala. It is NOT "just a holster". It has more "bag" and expandability than any of the other chest packs out there. Because it is one of the largest chest packs, it can fit my really big revolvers and act as the primary holster.
I'm in my mid 40's and only getting older. I don't like crap in my pockets when outdoors because they have to come out when I hit the sleeping bag and they can fall out and get lost. Just my keys, wallet, eyeglass case, cell phone, PSK and snacks alone (which always come out with) cuts out pretty much all other chest packs in terms of capacity. That is why I went back to the Koala --> it can hold everything.
Mine also carries my primary firestarting equipment, FAK+meds, compasses, other survival gear, gun/archery spares/tools, a 5x7 tarp+pegs+line, big knive(s) or little axes, dental hygiene kit, wipes, camp towel, a folding kuksa+instant coffee+spork, notebook+pen, tags, spare mittens (strapped on), flask, small bladder bag, sometimes my snivel gear (strapped on), sometimes the rangefinder and the snow goggles.
One can easily carry minimal overnight gear using only the Koala when it is above 50°F - use the straps to attach bulky stuff.
The Koala isn't "just a chest holster+". It is a major component in the organization of my first line camp/hunt gear.
In actual use, I carry it as an across the shoulder bag (w/ spare straps in front pocket) unless it is clipped up front unto the front shoulder straps of my pack.