I've always found the air bars a bit ironic, they have to be close to the cutterbar, but to they interfere with crop flow at all? I don't know much about them, but figured they'd have to move a PILE of air to work well.
I've heard with air stuff you get what you pay for, but it depends on how much of a performance increase you need/want.
And on the 8th day, God looked down on his planned paradise, and said "I need a caretaker." So God made a farmer.