Seats are not 100% safe, a friend of mine got his leg trapped between the seat in font of him and concreate step to his seat in the Block Z of the Sirrel and broke his leg really bad. A few months later we were at Wembley for one of the Anglo Italian Cup finals I think it was and were waiting for him outside the pub. He never turned up and were later told he'd fallen off a roof as he was a roofer and died

I can't help but believe his accident was partly to blame as he wasn't walking 100% afterwards
Standing at the bottom half of the the Kop would be good though for those that want to. Personally I prefer to sit these days but maybe because there hasn't been much to jump around to in recent years, haha!