«R. Farber posits that there are two different functions for the Shaliach Tsibbur: 1) The classic function to say certain prayers out loud either on behalf of the congregation as a whole, e.g. Kaddish and Barkhu, or on behalf of individuals who do not know how to recite the prayer on his or her own,… 2) to set the pace and melodies of the prayers. He then assumes different rules for the individuals who perform these two different functions.
But R. Farber presents no sources for this dichotomy in halakha or for women being allowed to fill role #2. »
Hirhurim - Torah Musings » Partnership Minyanim II