Yes if ADR is successful, you will not go to Appeal board. Please understand that what you are going to do now is challange the judgement of the Visa Officer. So whatever points they mentioned in the reason to denie your husband the PR, you ahve to prove each and everyone of them wrong. So get ready for a stressfull battle. I hope the consulant you hired knows what he is dealing with. Discuss every single even small things with him. You should mentally gfet ready to answer all possible wired questions they might ask.
To be honest, it is stressfull, difficult process but its not impossible. Most of the genuine cases in ADR are successful. Your appeal is sent to ADR and if they see that you have a strong case and going to appeal board will be wastage of time and money, only then they allow you ADR process. So, be careful and well prepared when you file the appeal. You must counter attack each reason for refusal in the letter and more. Start collecting all the evidence and other material to prove its genuine case.
Wish you good luck!