You have to remember they have totally different flight paths. The Firebird will want to start going Left (from a RHBH throw) when it leaves your hand. A is more of a Teebird esque flight because it wants to hold straight for a while before hyzering off.
When I first started throwing my firebird, I considered it useless for anything but overhand shots. I had nowhere near the skill or power developed to be backhanding an overstable disc like the firebird. I eventually replaced it with a Pulse, mostly b/c I liked the grip of the ESP plastic for thumbers. It was only when I decided to throw it backhand about a month or so ago that I discovered this disc's true potental. Thrown flat or with some hyzer, it will fly straight as an arrow for a good 250' before finishing with a reliable hyzer ( I drive 290'-330' on average). And like someone said, it does this while being completely oblivious to the wind. It sits on one side of a Teebird in my bag, with a leopard on the other. Anyone know what it would cost me to get those three in this mystical CE plastic?