If you are a professional athlete I suppose one of these things is something a club could take issue with one of their players using. Other than that, I see no harm. Just be careful, and wear protective gear. Here in Sweden there was the same outcry when every kid in a villa got a trampoline. Sure, there were injuries, but mainly because there are stupid people around who decided they were too cheap to also get the protective net. Great fun though, and we all know that everything that IS great fun comes with a bit of danger. That's not a reason not to do it IMO.