I've only seen pictures. That said, the problem I had with the venting on the original Rally was that it did not have sleeve vents. (It's amazing the benefit of sleeve vents!) The AR2 looks to me to combine the best venting of the Rally and the Badlands, so I have high hopes.
If I could add the harness and external water bladder pocket of the Rally to my Badlands, I would. This seems to accomplish the same but with better (ie bigger) armour is a win-win.