Caution: Weighted Footballs and other "aids"

I have seen QB's being trained to drop back with bungie cords and throw with weighted footballs. To this I say "HOLD ON". Throwing with a weighted football will do more to damage your throwing motion and maybe injure your elbow and shoulder than to improve your strength and/or power. It will most likely make you throw off-balanced to compensate, but most surely puts more strain on those two joints.
In similar regard, I do not agree with using bungie cords to add resistance to your drop back. More than likely, it will cause you to lean too much away from the line of scrimmage and change your balance. The more resistance, the more you must gain leverage to push against it.
I would encourage any and all bungie work while training to run faster, but do not use it to train your drop back! I am all for foot quickness, running speed and plyometric power and strength, but not at the expense of reducing your balance and not at the risk of injury to your arm.