Well, I didn't think that alone automatically made it easier, though I do think that no conjugation plus the amount of familiarity in the vocabulary are major factors, not to mention using the same alphabet. So from the admittedly short amount of time I spent on Haitian it felt like a similar difficulty to French, but then I probably didn't get beyond the basics enough to be exposed to the higher difficulty level of syntax you talked about.

But yes, syntax is huge. I spent years on Mandarin, even with a willing native speaker friend to help out, but finally accepted that it was beyond my capabilities (being already in my 40's at the time didn't help either). And it wasn't even the tones so much; the measure words/classifiers you mentioned weren't much problem either. It was indeed the syntax (except for simple straightforward sentences). Often I could recognize every character in a sentence and know its individual meaning, but still be at a loss to understand the overall meaning of the sentence. And with verbs, Haitian clearly marks exactly which tense/aspect is meant, in a system that an English speaker can understand intuitively. Mandarin not so much!