I use 3 different bags depending on the situation, and don't need anything else bag wise. As stated above, I use them for a multitude of reasons. I use the Tactical Udder for increasing surface area on barricades, tree branches, pipes, or rocks. This allows for a slightly flatter/more stable support for the rifle. Then I use the "gamer bag" for different open body locations in funky positions, for example between elbow and knee when in a high kneeling position, or between my butt and my left foot in a similar position. The other spot I use it is when a bipod tends to hop like on a car hood or roof. The bag absorbs the energy and allows for a straight back recoil impulse that allows you to spot a miss or impact a bit better than off a bipod when you can't properly load it. The rear bag I use for a rear bag but also for filling body voids from time to time or under a knee when I need to get an inch or two higher, etc.
My rear bag is a Traust - very light weight, locks up tight with a bit of squeeze pressure and very versatile. The fill and the lighter weight fabric make for a great combination.
My "big bag" is also a Traust - The "Gamer Bag" is like a pump pillow but has a lot of extra features that come in handy (sling strap, center "belt" to cinch it up tight and make it stand up taller/more solid, easily refillable, etc)
For barricades, rocks, pipes, etc I use the "tactical udder" or saracen bag.
The guy behind Traust is a good friend of mine and myself and a few other Colorado based shooters have all had input into his gear. He's taken all that input and put it into a complete package that seems to make all of us pretty happy. Give them a look.
All Available from Bison Tactical and Mile High also carries the Traust bags.
https://www.bisontactical.com/collec...ka-saracen-bag https://www.bisontactical.com/produc...ng-accessories https://www.milehighshooting.com/traust-position-bags/ https://www.milehighshooting.com/traust-rear-bags/ 
