I have never had trouble with any Wiccan, witch, or other practitioner of energy manipulation or the ritual arts. But I have known a few psionic vampires who did spark bad reactions. But those were usually the same psi's that I hated myself, and any reasonable person would have rejected some of them. I find that psi's are basically people, and witches will judge them on their own merits. Asshole psivampires are treated like assholes, but if you're cool, then you're cool, no questions asked.
OTOH, if you've got something to offer, knowledge or resources or abilities, then almost any Wiccan circle will make room for you. ^_^
Now, sangs are a different story. I suppose that would depend on your witches. Christian Mystics would scream and run, but anyone too close to the Left Hand Path would latch onto a sang and try to bring it home, ja ne?
I don't think there's any reason to believe in any intrinsic enmity or an innate collaboration between witches and vampires.
$.02