I think Warrington fans have such a strong reaction to Saints fans because they're very, very similar. Saints fans all grew up with a massive inferiority complex over Wigan and turned mega arrogant when we started winning lots of trophies. Warrington fans were similar, but with Wigan, then Saints lording it over them. So when the Challenge Cup wins came the arrogance quickly sprouted, only to be dashed each year when you somehow managed to drop out of the title race. Once you win your first Super League title, your transformation will be complete and the arrogance will bloom.
The similarities between Saints and Wire fans also shows in the reactions. Look at this board in the aftermath of the semi final. Then look at it after the 6-2 uber-domination of Saints, Duckie is again on about the inevitability of you winning the title and even some of the more normal posters are discussing how Saints and Wigan are finished and the rest of the league are trash.