I won't argue with you that difficult child 2 is a model student--all kids are different but it seems to me that difficult child 2 has some pretty heavy diagnosis's and medications. These are Rx'd by someone. That someone should now bail out ex-difficult child by writing the appropriate letter.
The type of teacher you are referring to can set a difficult child up for school refusal and many more things. She will not "improve him." He will get so wound up, he will be unable to learn anything from her. Have you read The Explosive Child? Your child may not be this severe yet, but in my opinion that is where unproductive pressure of this type leads. been there done that and my ex-difficult child is almost 20. If I could do it all again, I would get him away from hyper-critical teachers.
Martie