At one of my visits, arriving shortly before midnight, wit a departure 09-ish next day, I had decided to use the Meet&Greet service.
At that particular time it worked well, since normal immigration queues were overfilled with schoolchildren and teachers. The meet-up guy took us through immigration via the desk for pax with diplomatic passports, swifter than normal desks with few queuing.
On the other times, just as well without that service.