I can think of no good reason to send troops to Haiti.
The country is having a completely domestic political problem. It is tragic that this will no doubt have an adverse effect on the civilian population caught in the middle. That said, it is irresponsible and dangerous to place "peacekeepers" or any other troops in harms way for a conflict that is clearly in the earliest stages and which is rapidly deteriorating into a full blown civil war.
It‘s a matter for the people of Haiti to sort out for themselves as to who and how they want their country run.
When the shooting is over and they need assistance is reestablishing order and democracy, THAT is the time, in my opinion, when the world can best help and make the most use of its resources.
In general, I do not advocate any interference with sovereign nations without just cause. Just cause is not simply because a nation is having problems keeping law and order. A just cause would be sponsored terrorism (Iraq, Afghanistan), ethnic cleansing (Former Yugoslavia, et al), or humanitarian assistance in the absence of any form of government whatsoever (Somalia). Additionally, if the conflict involved more than one country, then it should certainly become a matter for the UN to resolve through demilitarization, de-escalation, and intervention with peacekeepers.
Haiti doesn‘t meet any of these criteria, and as has been pointed out already, we‘ve been there before.
Once the country has decided, through either a political solution, or a coup d‘etat, who they want running the show, then is the time to step in and offer a hand.