The portable resi has many uses. It can be used for training landings, putting it under a beam/bar and you can use it for conditioning. It is very versitile and every gymnast has used one in his/her career. Every gym should have a couple of these.
American Athletic Training Pit
Pros: Firm for landings, great for doing floor onto a raised surface for drills and the same for parallel bars
Cons: Older ones used to have the foam in the middle separate and you would get sunken sections.
I think this is a great mat for a number of reasons. First, it is great for drills. When doing floor, you can tumble onto it to work on you set or to gain confidence on a skill by performing the basic skill below it onto a higer surface. I also used this for parallel bars. I placed it at bar level to work on the shrug and pop of my dismount and it is good if you might fall off when learning a Gatson, Diant Diaminov, or stutz out. Additionally, you can use it to stack up behind the vault to work your block. Some of them come with a yellow strip down to side you you can further simulate yurchenko style vaults. I recommend this for every gym.