I have interacted with many types of birds and I must say that amazons are my favorite (just don't tell the other birds). There are three in my household (two are mine), Winston: red lored, Oliver: yellow crowned, and Harley: yellow naped. They are independent and keep themselves occupied, but also love hanging out with their humans (and they are generally good talkers, but that isn't so important to me and Winston only has an unintelligible hello and good boy).
That being said, when an amazon is not in the mood to interact DON'T push them or you will probably be bitten. They have strong opinions and can be somewhat hot tempered (if you can really describe a bird that way). It is generally easy (with some practice) to read an amazon's body language, so if you respect them and let them be when they need their space you shouldn't be bitten frequently. As for their behavior upon reaching maturity, I have not encountered any big issues so far. Harley is the oldest (7, so I assume she has reached maturity). The other two are males, but I am not sure if they are mature yet (I think Winston is, but I'm not sure about Oliver, although he does woo Harley

). The important thing to remember about hormonal aggression is that it generally passes with the mating season-be sure to give them space/respect and it is a good idea to perch train amazons for those times that you need to move them, but they are being aggressive (I have had episodes like that with both Oliver and Winston).
One option if you're worried about a mature amazon becoming aggressive is to buy/adopt an older, already mature bird. This way you better know what exactly you are getting. Harley is a rescue and an absolute delight. My mother and I both badly wanted nape personality in our house, but were both a little concerned, for the same reason you are. To determine if an amazon is indeed the bird for you I highly recommend that, if possible, you spend time with some and you may want to try for a hen. When I first decided to bring home a bird I did a lot of research and decided that a pionus was the right bird for me. However, when I went to see a baby blue head pionus I fell in love with Winston. A pionus probably would have been a good choice for me too, but I can't imagine not living with amazons now. Not being overly afraid of their beaks in the first place and really doing your research really do go a long way when interacting with amazons.
Sorry for the long-winded response.
Good luck with your decision! If you have any other questions feel free to ask. As you can tell, I never tire of discussing my amazons

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PS That is horrible! I can't imagine what it would be like if somebody stole my buddies. Just thinking about it makes me want to cry.
