AAR is about formation flying skills.
My experience is that is is harder in BMS than in the real Sim.
I have over 12 hours in the real Sim and I can hook up within 10 seconds after being cleared in.
So why is BMS harder. In my honest opinion its not BMS that is harder, but its because of the larger travel on the throttle in the real. Most of us, dont have the large travel. The larger travel makes it so much easyer to find the sweetspot.
I was told that some of the pilots dont want to do the AAR in the simulator because its to hard compared to RL AAR go figure