One of the biggest advantages GP2 has over FR 3.5 (Other than car performance) is that its the official F1 support series, This holds a couple advantages.
The drivers get to run on most of the F1 circuits so for the most part there not jumping into an F1 car on circuits they have never seen, There also around the F1 paddock so get to see how F1 teams work over an F1 weekend, This is even better for GP2 drivers already part of an F1 team as there able to spend time in the F1 garages listning to how engineer's work & how the F1 drivers give feedback about the car.
Something equally as important however is that F1 teams get to see the GP2 drivers for themselfs, They pay attention to the races & also talk to GP2 team personnel to find out exactly what a driver they may be intrested in is like to work with, What sort of feedback he gives & how good he is with car setup.
When we had unlimited testing it was easier for a driver to come from something like F3 or FR but with such limited running avaliable in F1 cars now stuff like this is crucial & this is why I can't see anything else taking over from GP2 in terms of been the main feeder series.
Edited by GTRacer, 28 January 2012 - 18:53.