Is it worth the effort to get the court to admit the copy of the will, or is it better to file as intestate and end up with the same heirs?

Well, your Dad is going to sign an affidavit, a sworn statement to the court. If he says "there was no will," that would be perjury. There is no provision in the small estate affidavit statutes for using a copy of a will. I would either do a full probate of the copy of the will, or do the affidavit and state that the original will can't be found, so you're treating the estate as intestate. When you say "mother and father are heirs," I assume you mean that mother and father are THE ONLY heirs at law your brother was not married, and had no children.