I have done multiple appeals in Montgomery County. In general, the school board has the right to get involved if the reduction in property value is greater than $50k. School boards, especially in more urban districts are very aggressive looking for tax dollars.
The school board attorney is just another party to the hearing. Typically, the county will have their people speak as to the value of the property, you will obviously be able to present your case, and then the school board will be able to present a 3rd opinion of value.
Your set of facts surrounding your property tax valuation will determine your success. The biggest advantage that you have as the property owner is that you have the ability to present information to the other parties about the property that they cannot ascertain on their own.
In general, Montgomery County is a bit more aggressive than other counties however, if you have good facts regarding your valuation, you will likely win, or at least get some type of relief.