For the Bahamas and Caribbean, we prefer early dining. The service is a little faster during main dining, as they have to be ready for late dining. The service is not rushed, just a little faster.
We find that the late dining stretches easily to 10 pm, sometimes 10:15, which starts to interfere with evening activities like the Pirate Party. Plus, how am I supposed to have a snack at a 10:00 Pirate Party if I just walked out of a four course dinner??
In the Mediterranean or anywhere with port adventures that last until 6:00 or 7:00, we prefer the late seating so that we don't have to rush back from the port.