I don't have any first hand experience. However, my father just have a bunch of tree work on his oaks done. He didn't have any oak wilt but it was in his area and he wanted to take a preemptive action. The arborist he used did say a diagnosed tree can be saved, but it's not 100% type thing. Also, it's just an evitability that oak wilt will eventually spread across the entire state and the current 2-3 year drought is has really push a lot of oaks to the edge and not helped the matter.