I'm only about a year into my first foray with funk (alliteration. yeeeeeah), a wheat I just wasn't happy with, so I dumped a Brett blend, some extra LME, a mess of raspberries, a giant pixie stick...i think that's it...anyway, that's the extent of my funk experience. With the timeline on this stout (need it by September), and the time to brew / fermenters I have, I'm not sure bugs are a good idea.
I was toying with the idea of using some black spiced rum (a shot @10m in the boil, and to soak some wood in) to get some of the vanilla and spices out of it.
Edit: If this recipe works out, when I finally bottle that sour, I might try to roselare one, like Tart of Darkness.