Cohesive gel or silicone implants?

Has anyone had them done. Im getting my butt done and I want it to be as soft as possible so I'm considering cohesive gel but it's not FDA approved which worries me. Does cohesive gel actually feel softer than silicone? What if the cohesive gel migrates? Is the risk just as high as butt injections? Please any information or experience you have will be helpful.