In Chabad-Lubavitch synagogues, it is customary that anyone who would not wear a talis normally does not do so just because he's leading/representing the congregation. The only exception of which I'm aware is the first day of s'lichos before Rosh Hashana: then (in the middle of the night), the shaliach tzibur wears a talis even though no one else does (and so he wouldn't, either, were he not leading the services). Why is that exception made?
(Note that I'm not asking the following: "Lubavitchers are careful for reasons of kabala not to wear a talis at night. Why is an exception made by the shaliach tzibur on the first night of s'lichos?" That's also an interesting question, but is not mine here.)