I was on a Cathay Pacific flight to China in 2009 where the seats slid forward but the back didn't lean back much at all. It was awful. The flight and everything around it was otherwise one of the best flight experiences I've had. But not being able to recline your seat for 12+ hours lead to very little sleep and back pain for pretty much everyone in my travel group. In fact I think of the four people I traveled with I was the only one who got any sleep at all.