Vulpinus and unimaculatus are basically the same species and are concidered to be rather reef safe. IMO there is no such thing as a reef safe fish! I always say, that if it has a mouth, it is going to eat something. Seems to me that you already knew the answer...
I have friends who have kept other foxface species succesfully with LPS, SPS and soft corals, but there is still a risk that they may go after some delicious ones, such as Lobophyllia.
Rabbitfishes are a different story. I wouldn't call them reef safe at all. There were some Orange spots in my LFS a few months ago (the two similar species, can't remember names, punctatus?) and they went postal!! One ate a big Elegance coral as sopn as it got to the tank, and others did some damego too. I got a lot of thanks after I got on time to stop a couple friends of mine from getting one!! LFS sold them as 100% reef safe, saying that all Foxfaces and Rabbitfishes eat only algae. Well they don't...
I would say, that the ones that are the same shape as vulpinus are more reef safe. I have one, and it hasn't touched any corals so far...