The Tzemach Tzedek (1789-1866; 3rd Chabad-Lubavitcher Rebbe) in a lengthy Tshuva (Yoreh Deah, Siman 93: http://www.hebrewbooks.org/pdfpager.aspx?req=1614&st=&pgnum=164) discusses the matter of shaving and concludes that it is strictly forbidden to shave the beard and furthermore concludes that one must be strict not to trim around the beard as there is uncertainty where the "corners" of the face begin and end. This is the normative practice among Chabad-Lubavitch Chassidim.

Are there other groups of Chassidim and non-Chassidim that adhere strictly to the Tzemach Tzedek's practice?