DValdron and Cinaed, you two have been peeking at my notes for the "Voodoo Empire" Haitiwank TL I thought up, haven't you?

My ideas were very close to DV's, though I had them incorporate an independent Mayan Yucatan into the "Federation" during the Santa Anna era revolutions and never considered the canal.
I hope that you write it, it sounds like it could be a lot of fun. All too often the response to possibly interesting notions is negativity and nitpicking. That's disappointing. So, go for it. I'd love to read a Haiti Wank, doing it and making it somewhat plausible is an exercise in creativity.
Like stated Haiti has a lot going against it:
Which only makes it a challenge. But at some point, every empire or state has an undercurrent of improbability. Looking back, it seems like a ridiculously improbable Wank that a marginal European state like England could end up a world dominating superpower in the 19th and early 20th century.
* A highly divided population with mutually-distrustful white landowners, black former slaves, and mulatto mercantile middle class. L'Overture and maybe Christophe were the only ones capable of bridging the gap.
The interests of the white landowners and black former slaves seem utterly incompatible, and the fracture lines go beyond economic to social, political, historical and racial. It's hard to imagine a Haiti where they come through without serious transformation.
* The island's wealth was sugar and tobacco. These need plantation production. Only the lash and gun is likely to get disgruntled former slaves back on the plantations (though Cinaed's "profit sharing" policy holds some promise).
Perhaps communals or collectives? This is incompatible with western traditions of hierarchy and private ownership. Nevertheless, there are western examples of collective or communal agriculture, particularly with groups like the Quakers, Mennonites, Amish, Hutterites, Doukhoubors. I'm not at all certain that any of these were around or their models developed in the pre-revolutionary era.
However, I'm prepared to take a wild stab and say that an economic model like this has tended to occur naturally from time to time and could take place here.
Would it work? Potentially.
The plantation model had to invest heavily in guns and lashes obviously, so there was a lot of infrastruture and capital overhead involved. That's the thing that everyone overlooks in slavery - sure, slaves are free labour, but it costs a lot of money to keep them in chains and make sure they stay there. Even if you persuade the state to do a lot of your slave enforcement for you (the only way its ever viable), you still run a lot of overhead.
On the other hand, the plantation model proved incredibly lucrative and a lot of wealth flowed through. It wasn't a marginal break-even proposition. So conceivably, redirecting that wealth surplus into a communal enterprise could contribute to viability.
So, with substantially reduced overhead, and therefore more profits to support a standard of living, a communal model could well supplant both plantation/slave operations and individual subsistence economies.
Of course, the point is that slaves and slavery would have some very bad antipathies to plantation or pseudo-plantations. But if even a few communal operations were able to establish themselves and compete with the slave operations, their model might have been very persuasive.
Of course, would the relative wealth of a communal plantation operation be meaningful. The average person doesn't care about foreign trade or revenue. They'd just like a decent standard of living. So its not clear what or how much a communal operation could offer in 18th century Haiti over a subsistence farm operation.
Conceivably communal operations might offer more safety and security than an individually owned subsistence farm operation. Particularly in a Haiti where slavery was not dying an easy death, or which lingered on the edges of civil war and with poor security.
Or it might be strongly religiously motivated. Voodo Communism anyone?
Or possibly there's just a strong emerging demand for consumer goods that subsistence farming can't suppy - china, fabrics and clothing, brass, firearms, etc. etc.
I would think some combination of these factors, with their relative strengths would all be in play, in ways that would shift over time.
What this seems to indicate is Haiti as a hotbed of proto-socialism, likely with strong Voodoo influence.
So maybe the real POD would be some minor regulatory or administrative change that allows these sorts of communal operations to develop and participate in the mainstream Haitian economy, prior to the French revolution?
* An independent republic of former slaves after a violent uprising was a direct and symbolic threat to the slave aristocracy across the Americas. Everyone among the world and regional powers had reason to see them fail.
True, but within a mere two generations, that slave aristocracy would be in deep trouble. Latin America erupted in revolution as early as the 1820's, and by the 1830's, an emancipation movement was well established in England.
The situation was nowhere near stable, and while such an independent republic was a direct and symbolic threat that everyone wanted to see fail.... well, the truth was that just about everyone else was courting failure. A robust and powerful Haiti might well have been perfectly positioned to ride the winds of change.