I can understand being apprehensive about giving other civs a way to acquire another civ's UU. However I don't think it's the biggest concern as the current iteration of Mercenaries allows for this anyways, just on a more random basis. I'd be all for having special contracts for UU's that were historically mercenaries, such as the Varangian Guard and the Gallowglass, provided that these contracts only appeared if their relevant civ was not in game. Thanks for the offer Zwei! I'll try and get you a little write up on them after I've gotten a little more sleep.