My dad was a blacksmith so I have been around horses all my life and have had my own horses.
Your list is correct and the last thing (OH BOY EXPENSIVE) You hit the nail on the head.
A sick horse cab suck you dry faster than any grey.
You can buy a cage for a grey but you build a barn for a horse
A grey will fly around the house, but a horse you buy lots of land just so they can walk around and eat.
You put up a fence on that land so they do not get out and on to the road and get hit. OH the insurance you need.
A grey you just close the cage door.
In January when its 15 below zero you still have to go out in the cold to feed and water and than in the cold you clean stalls.
I will take a grey, amazon, cockatiels a dog a cat any day of the week. But I do love horses.