As a Jersey guy who stumbled on this thread (and is on CX JFK-HKG in Nov) I can tell you getting the train to JFK, for me, is a real pain. This means New Jersey Transit from Trenton to New York Penn Station, which is 90 min. Then the AirTrain which takes forever from there to JFK. Then you have to get there 2ish hours early.
40 minute train to EWR. Done.