Found this info on the Oxygen blog about safety. http://oxygenfreejumping.co.uk/blog/jumping-safely/#
Like Flipout that sent three to hospital with spinal injury in just one day. Have a friend who's husband works in orthopedics, their children are banned from these places after all the awful injury's he has to deal with caused by trampolines.
Have a google for the stories about the accidents in these places and you will never go back again. One of them had 100 accidents 7 serious in 3 weeks and the owner said it was better than the national average, just before the local council closed them down.