Only used it for my MSF course so far. During that time frame, the air flow was good. I ended up pulling most of the armour out, to help aid with air flow at the lower speeds.
My only real complaint, the armour & pockets. With both liners out, the mesh in the elbow area, will dig into your elbows from how stiff the elbow armour is. Not sure if I was exceeding the designed range of motion for the jacket, but I ended up popping open the elbow & shoulder armor pockets, while wearing the jacket. So all 4 armour bits started to slide about.