playing a lot of time with mesmer thieves was my pain.
Shatter had nice burst, but 1 error = death.
Condition PU has good survival, but enemie just run after understanding the situation. Interrupt – good build, but in roaming WvW not enough escape abilities.
After using this builds thieves became my welcome guest. Others too, but 90% of thieves use bers armor and have the lowest hp as ele. With good managing of skills you can kill some condition-dealer-classes faster, then they put full condition bomb to you. In my opinion threat is P/D condition thief, but I didn’t see big numbers of them.