Quite a lot of variables in this situation. Runway length, weather being a few! For an unextinguishable engine fire the scenario is black and white, for an engine failure it really is down to the commanders discretion. A factor to consider are where can I dump fuel. If I have to fly 100 nm to dump fuel then no, if I can dump fuel in the locality of an airfield then why not. I think 411a has it right, there is no particular rush but also there is normally no problem landing overweight. Personally I do not like to fly away from an airfield, one possible reason for the engine failure could be poor maintenance, 411a will probably expand more, but I remember an L1011 (poss EAL), losing engine after engine on the way to the Bahamas, and only just landing at MIA after a cock-up with oil seals. Also a Queens flight 146 doing similar and landing with virtually no power.