Having never flown a model Helicopter, I started learning to fly a Helicopter on the G2 Sim, and then I bought Aerofly Pro, I got quite good IMO and was very confident of being able to fly a model helicopter.
So off I went to the model shop, and I purchased a Humminbgbird V3
But I really struggled to control the Heli, all the practise on the Sim had hardly done anything
So I then purchased Reflex, and found that I could'nt fly the Helis to save my life, just like I had just found out!
After hours and hours of more Heli practise on Reflex, I re-learned how to fly a Heli (again!), and when I got back onto the Hummingbird, I found that I could fly it reasonably well.
So I would definitely say Reflex is the most realistic Sim at the moment.

Andy