This is a minor fascination of mine. As far as I can tell, everything built pre-privatisation, and also Desiros and the Hitachi 80x, will open the doors immediately if the button is held when they are released. This includes 323s - I remember this clearly because now they're PRM-modded, a door opening beep has been bodged in, and if you hold the button down then the door actually starts opening before the beeping.
In contrast, Aventrae, along with CAF's stuff, seem to require that the press occurs after door release.
I can't remember what the older Bombardier or Alstom units do. On Stadler, the door obviously won't open immediately, because of the sliding step, but I don't know exactly how it does behave.