There is definitely a surlier tone to Separation Two, probably because he couldn't wait to get it over with. I note that Balls! is dedicated "to my critics" - maybe the sloppiness and inconsistencies were wearing a little thin with reviewers at the time. I'm assuming that by this point there were less reviews of the book than his previous ones - and that there were even enough stringers who cared enough to keep up with his output to point them out.
If I can step back a moment to Separation - the entire Rashida plot takes up an awful lot of pages for a book ostensibly about a crisis of Canadian unity. Of course, every time we picked up that story it we had to endure scenes of interminable negotiations - I'm betting Rohmer himself had had enough of the division of CNR and Air Canada assets and wanted to get back to the Bond-like casino setting of Rashida's story.
Picking up on Chris's question about his turn toward the rougher, I will say that Rashida's confrontation with the security guard in her hotel room was more brutal than I was expecting. I'm not sure if it suits him - rather than seeming natural, it seems affected. Sort of like Roger Moore trying to look cool at Fillet of Soul in Live and Let Die.