Well, I will not say how faster or slower the A343 is vs the 742, however, I must say, that most of the Greek Americans had loved the Jumbo, and re rather unwilling to get over with the new Airbus.
Recently a friend of mine came from Greece, and told me that "the Airbus did not give him the same safety feeling than the 747........ "
However, I must say, that from what I have heard, the service is good, the food decent, they serve Ouzo drinks as well
, PTVs in economy, and all the times that I went to JFK this summer to pick up friends from ATH, the flight was on-time, sometimes came earlier.... (strange for Olympic)
I hope you will enjoy your flight, especially if you are flying Business.