Monroville:

This would in turn give the Falcon the needed time to escape (can't show the reactor topple, fall and then explode behind them, as the whole DS would go up instantly, destroying everthing around and inside it, including the Falcon).

Well it seemed to work perfectly well that way in Return of the Jedi. You seem to be suggesting that the destruction of the reactor would cause an instantaneous vapourisation of the entire Death Star. Why would that happen?

I think the way it's depicted in Jedi, with the chain reaction explosion spreading outwards, is completely believable. That's how it works in Star Wars, as well, remember.

There's nothing to suggest that the Death Star should instantly blow up. The drama doesn't support it, the facts presented in the movie don't support it and physics don't support it.

But if that's what you'd have in your edit, great.