unless am reading it wrong BUT troubadour reduces magical/physical vulnerability by 10% which mean your group member gain 10% more magical/physical dmg for 30s, so yes troubadour does bring dmg boost for ur group lol.

yes i know they both share the same class role but let be honest here, MP/TP regen isnt going to be as "useful" for BRD/MCH in 4.0 just because the cd is like 180s which is pretty long also now that mages can gives mana to healer, i doubt that brd/mch has to worry about it. Anyway my point is that would you take a BRD with more support utilities or a MCH with less utilities but more raw dmg?