neville_nobody
As someone who has flown both the 330 and 340, I'm more concerned about a cargo fire then an engine shutdown. One is extremely time critical, the other isn’t. To some it may sound frightening only being on one engine over the pond or arctic, but the reality is having a cargo fire in such a region is by far your worst nightmare situation, irrespective of the number of engines you have.
TwoFiftyBelowTen
I can’t give you exact figures but numbers I've heard are that the 340’s maintenance costs are about 25% higher than the 330's.