My info is about 8 years out of date but for what it is worth with Marhaba I was escorted from the plane to the customs line then quite embarrassingly taken to the front of the queue, it might be better organised these days.

As Metanoia says it does depend on your arrival time. I have never had to wait that long though and sometimes a normal queue is quicker than the fast track queue but that is pretty self explanatory when you walk through and see the desks.