Where in Washington State are you? Which group do you work with to adopt your greys? You say your vet sees "a lot" of greys...but then was treated incorrectly for a TBD, which are fairly common in greys. In addition, a titer of 1:80 is still a pretty low titer for babesia. What symptoms of Babesia was Ethan showing when he was incorrectly treated with Doxy?
I used to live in Seattle and could recommend a place to take your grey for a second opinion if you'd like. In addition, I'd be happy to get you in touch with some friends affiliated with a group up there who have some fantastic vets they could also refer you to.
Best of luck with whatever you decide. After the incorrect treatment for the Babesia I'd be researching the heck out of anything my vet recommended at this point.