Kapanake's district is just too Democratic to be able to pull it off again considering the increasing polarization. Hopper is going up against the same opponent he had last time around, in which he won by .1%. While that may have been a terrible year for Republicans it was also before it was known the married Hopper was banging a twenty something who he helped get a state job.
Again, if Kapanke managed to pull it off in 2008, the worst year for Republicans in recent memory, it can very easily happen again. Any belief that only Democratic-leaning voters are energized by recall mania should have been easily disabused after Prosser kept his seat on the high court. There is energy on both sides - and recalls work both ways.
Hopper might have sex scandal issues, but the Republican base will ignore that and come out to vote for him anyway. Or Republicans might primary him if it looks like he will lose.
Kapanake's race was quite close as well in 2008, but again its just too much polarization now for him to win a district that Democratic. Both bases are going to turn out, but in that district the Dem base is much larger. As you pointed out Prosser/Kloppenburg, Kloppenburg won the district by 15.6. The district is way too Democratic for Kapanake to survive. He is done, and it won't be close.
As far as Hopper its going to come down to Independents. Granted they are unlikely to make up the amount of the electorate they would in a typical election as it will be dominated by the bases, however they will have some impact. And Independents aren't going to look to fondly on someone who gave his mistress a state job. Bases of either party may overlook something like that because its their guy, but those in the middle won't.