I'm building an NPC Vigilante for my next campaign, and I'm interested in stacking the Thwart Pursuit (Ex) ability (add half vigilante class level as a bonus to all checks in a chase and to Diplomacy DCs to gather info on the vigilante) from the Serial Killer archetype which appears in Ultimate Horror with the Chase Master (Ex) vigilante talent (add the greater of half your vigilante level or+4 to all chase checks) which appears in Ultimate Intrigue.
Thwart Pursuit doesn't explicitly forbid this, but adding the whole class level as a bonus to all of the character's che checks will make her awfully tough quarry to catch. As a 6th level vigilante, this would give her a +7 bonus to all checks in a chase. If PCs need to role 11s and the villain only needs to role 4s, that seems brutal, but not insurmountable.
Thoughts?
It's not a bad thing if the bad guy can get away a couple of times. It gives the players a chance to think of ways to negate the villains advantage. Magic will be significant. At 6th level fly is available which gives a +10 - even something like spider climb can give +10 to many challenges. Maybe let the players make know local checks to anticipate potential escape routes and set up things that will grant them circumstance bonuses.