To add, if any defence lawyer is going to challenge—“What did you get for this testimony?”—it goes straight to credibility. But the statutes I've reviewed in Australia actually have another mechanism for disclosure to other courts if a protectee, now having completed his testimony in one case, actually becomes a witness in a civil or criminal matter that's unrelated to his protection. The judge, at least, is told, so that he can advise the counsel that this man is a protectee and there may be issues with his credibility.
On June 5th, 2007. See this statement in context.