You'll see a bunch of suggestions throughout this forum on starter vs. no starter for plambics and flanders beers. There was the "Roselare - 2 ways" thread which discussed this a little bit, too.
I'm not sure there's a consensus.
But I DO think people would agree that, ultimately, you want your primary FG to be relatively high to allow plenty of food for the bacteria and wild yeasts to consume. The madfermentationist blog entry on sour beer production goes into some practical detail as well.
High FG is not a wild-beer specific concept...you can accomplish that thru mash, recipe, or yeast cell count modifications.
A yeast starter, however, will likely only benefit the saccaromyces, which are one of the several organisms in the Roselare blend.