My problem with Stars was that I lost track of who was who in the zoo. Nearly every chapter brought new characters, with new conflicts. There were at least three main plot lines opened, and no obvious link between them. Also, I kept feeling that I was missing important bits of back-story, namely the war and relationships between the humans and the aliens.
Now, Goblin Emperor is by no means light reading. It has name issues, in that characters have different names and titles based on marital status and age. Having said that, I found it much less opaque. This was for two reasons - one, Sarah Monette (Addison is an open pen name) kept the point-of-view to one character, who as an outsider needed to have stuff explained to him. Second, the story was not set in a world where there were seven previous books written.
What does this mean for the Hugos? Simple. No matter how popular the nominated novel is, there will be a sizable portion of the Hugo electorate who is reading it for the first time under the gun of having to make a vote. Works that require having "read along" or which are otherwise opaque will have a hard time getting votes. In a normal year, Stars would either be 4th on my ballot or just get left off. Since this is not a normal year, it will be below No Award.