People do not usually put the Gra and Rav Shach in the same category as Rav Nahman of Breslov. But to me that seems like a mistaken approach. True the Gra did sign the letter of excommunication the herem which certainly has halachic validity and ought to be heeded to at all cost. Still Rav Nahman certainly was not in the category of the herem.

The Gra and Rav Nahman have different areas of emphasis. Rav Nahman with prayer, and the Gra with Torah. Happy is one that can combine both.