I post this with some of the benefits and negatives on this approach:
+'s:
A mind game leading to sh'd raptorboost can catch an opponent off guard, even if it's a grounded boost it can
possibly lead to further comboing.
-'s: (As much as I like the idea I don't see too many uses for it)
As mentioned, easily punished. Even more so if your opponent shields, leaving them to grab in the frames you're "falling" to the ground in front of them.
Sidestepped/Spot dodged easily, the frames in which Falcon hits are outdone by the invincibility time a dodging character has.
Tested: Seems to be only good on larger stages, leaving FD and PS the only legal stages to use it on.
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By all means, if you can use it effectively, go for it, it will only work to your benefit.
IMO it is still only useful to use a grounded boost, as it leads to our somewhat gimped air game.
EDIT:
Does hitting with aerial Raptor boost leave Falcon in the "can't do anything but DI" special-state?
To a degree yes, you'll receive your small pop up, and become immobilized afterwards. (Tried it earlier, can someone else test to confirm?)