Boambee looks interesting. It is highly rated on TUG. The other two aren't listed. Voyager is not 5* and ONLY has one BR sleep 4 units with a Sat check in. The Mariner isn't even listed in the body of the II book. It is not 5* and only gives the name and location. Surprisingly there are a number of other highely rated resorts. I wonder if DVC is actively avoiding Worldmark as they have a somewhat similar product.
I'm an Aussie & can say that Coffs Harbour is a nice place to visit, we've been there & it really is nice. It's 5 hrs south of Brisbane & probably about 8 -9 hrs north of Sydney.