Free recoil is best for shitty barricades that want to fall forward when try to load your rifle. That's why guys try to build rifles with as much COG just forward of the mag well. The rifle will balance on the barricade and you aren't fighting elevation(up or down) with your body position. This is also when it's best to put your support hand on top of the scope, to emphasize the COG. As much as I try to shoot pure FR in a stage, I'm almost always loading the rifle a bit more than I want; habit under stress.
Is free recoil a competition technique with little value in the "real world"? Is sling supported technique archaic? Well, a bunch of older, experienced shooters could probably share some beers and debate for hours. The guys with the best perspective would be those who have used and studied both enough to demonstrate a certain proficiency with either. I learned sling supported techniques first. Are they more realistic? Or did we just model our training from the current competition of the time, highpower. I would say a student of the rifle owes it to himself to learn both and when in Rome....
Kyle Lamb told us in training that the difference between a good shooter and an experienced shooter is that an experienced shooter knows what he can get away with. With a carbine and pistol, I agree. With a PR, I think an experienced shooter knows how and most importantly, WHEN to adapt the best technique to solve the current shooting problem.
You're asking in the context of wobbly barricades....who excels at shitbox, artificial barricades...PRS shooters. What does a gamechanger provide for you? A wider platform to balance the rifle on = free recoil. You don't need a GC to load a magwell into a barricade. A GC gives you wide, soft platform to balance a rifle. This is a FR tool.