In my opinion i believe the death of Sirius is not going to be more emotional than Cedric's death(in the film).
I believe this will be true becuase Sirius was not in the film too long. They should have put him in at the end. I believe the Goblet of Fire was not faithfull too the book. So the emotion we have expressed while reading the book will not be the same as film 6.
I think that the only death that will be far far beyond emotion will be the death of Dumbledore.
When i read the Goblet of Fire i did not express any signs of emotions to Cedric's death. But when i watched the film my views changes. When i found out out Dumbledore i was shocked! I couldint believe it.
That scene is pretty heartbreaking... but it gives the movie a kick.... i was sitting in the Cinema and couldn't wait to discuss the movie with my friends, but after the Death Scene and after movie when everybody was walking out, nobody said enything :-S... kind of spooky... you could see in peoples eyes that noboby really liked the ending.... personaly i hate it... Cedric's death was total Heartbreaking....