It seems that Buffyverse vampires are more like Red court than Black court in a way. White court is right out. Yes, they get made like the blacks, but otherwise they have much more in common with the reds.
Though in any case, it seems like their soul gets replaced with something else. Something that gives them their powers, but also something that is entirely inhuman. I could see turning a red or black into something like what we see in Thomas, a human soul fighting against the demon. So while you can't kick the demon out and replace it with a soul, you might be able to restore some sort of balance, having a human will bind the monster inside, enough to keep it in check.
Then again, this is the Dresdenverse. Virtually anything is possible. You could even stuff someone else's soul in there for good measure. Or maybe make a pact with a Sidhe to shut off the demonic half like Leah did. Or even a pact with a demon, a god, anything really. Maybe some sort of angelic co pilot who keeps the demon in check, so you can take control of the body and its new powers. Tons of possibilities.
