Mother Night: The prequel to Slaughterhouse Five?

As I read Slaughterhouse Five, I've always been curious of the motive behind Howard W. Campbell Jr . I really wanted to understand what made Campbell betray his own people, and work for the Germans.

Then, I found:

Summary: 
It is the fictional story of Howard W. Campbell Jr., an American, who moved to Germany directly after World War I and then later became alternately a well-known playwright and a Nazi propagandist. The action of the novel is narrated (through the use of metafiction) by Campbell himself. The premise is that he is writing his memoirs while awaiting trial for war crimes in an Israeli prison
Work Cited: http://en.wikipedia.org/wiki/Mother_Night#Plot_summary
------
Sounds pretty much like a prequel right?

Vonnegut claims that this is the ONLY book he wrote in which he knew the moral of the story. From very brief surface research, I also found many similarities between Mother Night and Slaughterhouse Five: 

1. Along with Slaughterhouse Five, this is one of the three book that Vonnegut was really satisfied with, giving it an "A+" himself
   
2.  Although it looks like this story doesn't have time travel, the protagonist started and ended in the same place. 
3. With a dark past, the protagonist found that he had no reason to continue living (after going through his adventures in the book), and surrendered himself.
4. The famous "so it goes..." 

From Slaughterhouse Five, I did not really like  Howard W. Campbell Jr. However, as I read further into the summary of Mother Night, I begin to think that everyone has their own story, and that you should not be judging a person based on the majorities opinion. I believe this is also another lesson that Vonnegut is teaching us through his books.

So now that I've said all that, anyone curious enough to pick up the book with their own free will?

poo-tee-wee
                                                                                   - Yuemin