I wonder what steps Harry took to test the limitations of his own Patronus. The thing is humanoid and it /speaks/. Is it conscious? Does it have memory, can you give it information, dispell it, call it back the next cay, and have it still know the information? Can it perform useful cognitive work, solve problems? Does it exist anywhere and in any way while not called forth by Harry's spell? (Can it think while Harry is asleep? what an asset that would be!)

And, dare I ask, can it recursively self-improve? ;) Okay, okay, stop it with the rotten tomatoes.

I'm sure the answer to most or all of that is "no" just because of the way it would affect the story but, if I were Harry, I'd test it anyway. It is a safer and more convenient magical-humanoid-that-speaks to examine than a Dementor, and Harry has given a lot of thought to how their minds work...