Personally, just like children, I want them secured in case of a panic stop or worse. Since my dog Thor weighs in at about 110, I don't want him flying towards me.
I have a slightly used barrier in my basement. He bumped up against it and it fell down. Absolutely not safe in my opinion.
I recently lost my second, Zeus, another 110+ lb Rottweiller. I had them both in separate crates. Of course, I did not try any long trips with them. When my wife and I traveled, they had fun at camp. (We never told them it was a kennel. That would upset them.)
