Let's start at the beginning, at Recruit. If you are already an absolutely pro at Smoky, don't get Firebird. This is because it is unlikely to suit you. After that, forget this thread. If you are not a pro at Smoky, try getting Firebird and see if it suits you. If it does, and you get lots of success with it, use it until you are starting to get rubbish with it, then switch weapons. Whatever the case, the most important thing is that you have to use a weapon that suits your gameplay at all times. Using a weapon you are useless at wielding is always a fail.