Of course I don't want to mess him up, but I also don't want him to perfect every single song. One perfectionist in the family is good enough. Thank you very much. Just for the record I don't want him to be a professional pianist either.
This part of your post bothers me, and I promise my response is not meant to be ugly.
When a child is good at something, and it sounds like your child is great at piano, you need to allow him to continue to grow that talent. If you don't, the piano playing will become boring and eventually stop. And whether or not that talent becomes his profession years down the line, the lessons, discipline, determination, his talent, etc, will teach him many useful skills when he is an adult.
If he perfects every single song, the first time he plays it, that doesn't make him a perfectionist. It makes him a musical phenom. If it doesn't take him long to perfect or learn a song, then he just has an amazing talent. And you've said he can read notes, which in itself is a gift. Not many people who play instruments can.
If he cries and screams and kicks the piano or himself IF he doesn't get song the first or second time he attempts to play, or he threatens to quit playing if he doesn't get through a song or lesson, then you have a perfectionist on your hands. If he refuses to do anything he's NOT good at because he might fail, then he is probably a perfectionist. As a parent, you need to give him opportunities to learn that he will not be so great in other areas and that it is ok not to be, but allowing him to master the piano or something he is good at will not make him a perfectionist.
And personally, if he loves the piano, and he's good at it, I'm not sure why you wouldn't want him to be a professional pianist or at least encourage him to continue to play and move on to the next level. Being a doctor, scientist, lawyer, etc, or making a 6 figure income is great, but what good is that job if you're not happy?
I'm extremely discouraged by any school or teacher wanting to slow a kid down that obviously can excel in any subject, whether it be math or music. And with music, there will be a time and a place to teach music theory and concepts, which are quite boring, especially for a child. If he was my DS, I'd find another teacher/school.
Good luck!
