Every case is different. IDEA Due Process litigation is very fact specific. Your question is beyond the limits of this forum without an individual review of your child's individual records.
When it is appropriate for your child with his particular circumstances. Experts can disagree. When they do, if you can't agree on an IEP - because your "independent" evaluator does not have more weight than the ones that work for the school - the court will decide. Get an education attorney who will file for a quick resolution. Till then the old IEP remains in effect.
This should not be considered legal advice and is intended for educational purposes only. It does not constitute a contract for legal services between any parties. Answers are given to questions for which there may be additional facts not mentioned which might change the legal issues or consequences.
You need to obtain a qualified Special Ed attorney through this website or contact the COPAA website. You need to file for a Due Process Hearing. But retain a qualified attorney first. Good luck!