As it is on live, there is no difference between the disabling skills of an Assassin and a mechanic. They both have the same disabling skills (unless you count junk like the Cabal trap).
Even if you put the faster search into a higher tier, Assassins/acrobats will take it anyway because Wand and Scroll Mastery is at tier3.
It's also not quite like making Assassinate or Knockdown immunity easily-accessible: faster searching is a completely new ability. And do you really want your PrE's core ability being "better trapmonkey?"