I have recording turned off and replay duration set to 0. I don't think there is any writing going on for that function. When I push "Replay" on my 536HP the screen displays that replay is off.
You are still writing via the replay function - you can't turn it off.
You DO have to manually start recoding.
That said - still on my orginal card in 3 HP1/2 - one is as old as possible , it was the first sold by that particular dealer. Hp2 was one of the first '2's as well.