Should I make that speech in French or Creole? (What do they say about public speaking in Haiti?)

In Creole, definitely!
If you have a Creole-speaking audience, it makes sense that your speech is done in Creole.

The Duvalier time is history.
The Makouts have been annihilated.
The Haitian people are now free
To speak their minds
In Creole.

Once I had to sit through a 45-minute sermon delivered by a Haitian native in French.  His French was nightmarishly horrendous!  It was so uncomfortable the audience was noticeably fidgeting in their seats.  I slapped myself that day for not sitting close enough to the door.  I could have escaped this torture!
This man had bouch sirèt (Haitian Creole expression for speaking terrible French).

So, make the speech in Creole. If not for your good name, do it for the sanity of the people in your audience.

Here are the benefits for giving your speech in creole:
-French-ised Creole makes you sound smart and sophisticated.
 But a badly "Creolised" French does the opposite.
-The Creole-speaking audience will understand your every word.
-You'll have the audience's full attention.
 They won't be whispering "what did he/she say?" to others while you're trying to give your speech.
-You jokes will not be lost in translation
-No bouch sirèt.
-Kreyòl spoken, Kreyòl understood