I haven't used FA at WDW, but I love them at DLR. They are registered nurses (something Walt Disney insisted upon, I've read) and are very careful.
Story: DS smacked his cheek, HARD, on a new ride at DCA, and he needed an ice pack. They gave us one, but also made SURE that what we said happened had actually happened, in order to protect DS. Having been through that questioning twice when DS was 3 and had two ER visits (one burn and one fall), we know that it's uncomfortable, but it is also a GOOD thing. We appreciated the care they took with him; they also palpated his face to make sure there was no fracture. (for those heading to DLR soon: Mater's Junkyard Jamboree has major forces that can slam you against the side, and the sides are 100% UNpadded) (for now)
I always wonder why people bring drugs and all of that with them, when you can jump into FA and get something for a headache or blister or stomachache, etc.