Bingowings:
The emphasis is on the sudden silence, it doesn't prove that the whole process was instantaneous.

Well, exactly Bingowings. I mean, if you really want to take Ben at his literal word, but honestly, what's the difference between a planet exploding instantaneously, and somewhat improbably, to a planet being obliterated by a shockwave in about five seconds? I mean, your entire planet blowing up in a few seconds isn't sudden? The timing with Ben then feeling the event in the Force is fine.

Monroville:
I can understand where you're coming from, but also think atomic bomb or anti-matter. Those don't take too much time to instantly vaporizing large areas.

No, they don't take too much time, but they do take some time, which is my entire thinking behind the new sequence.