I had one of Hollands, I really liked the size/shape of it. The camo pattern blended in a little too well with a WY hill so now I have a leather one that uses the 'ears' from a bag they sell at cabelas. I got the idea after using Ernie's a few years back...
If it is a long range hunt I always have a rear bag in my pack. I have a couple of different shapes and I guess my mood dictates wich one goes on what hunt. All of my bags are handmade by a guy over @24HR Campfire, he does a run of bags everynow and then, real nice stuff.
Here is a couple of pics . I have two rectagular sizes 5x7 and 7x9 and a round. The smaller bag has a strap that I leave attached to my back pack. These are filled wiht som esort of poly beads, a bit lighter and no problems when they get wet.
I use the Redman bag and have a small aluminum carabiner on the end strap. When it's is a pack it's just loose but if it's a short hike/walk I clip it on a belt loop, out of the way, and it's so light it's like it's not there but it is quickly available.
I have not used a "rear bag" per say when out hunting. But I do always try for some form of rear support, wether it be a pack, coat or combination of a few things to get stable. Most of my hunting is remote horse back and hiking, and I just dont want to pack another pound around all day. If I were hunting closer to a truck or quad, without question I would have one of the fancy Red Tac rear bags.
I used a Triad rear bag on my Antelope hunt in Wyoming a few weeks ago and it worked great. This was my first experience hunting like this but it seems to work great. I carried it in the cargo pocket of my pants and it never bothered me. Of course spending time in the Army I learned to carry many thing in the pocket and got used to it. It comes prefilled with a material that's not too heavy and works very well. I have used it both on it's side and flat. The bag squeezes easily for elevation adjustments. The picture is where I shot the doe at 300yds set up exactly as you see. I used exactly the same set up for the Buck I shot at 400yds.
I made one for this years hunt in the shape of a door stop with a para cord strap for easy attachment to my pack with a carribeaner. (sp) I got some cordora (sp) nylon material and figured it should last a long time.
I filled it with some old media I had and was very happy with it. It worked well on antelope and my first mule deer. ;-))) Man them guys are big ;-) glad it was all down hill back to the truck.