Guild Wars 2

is it worth popping assassins signet for the 15% more dmg vs just keeping the 180 power?

I’m of the opinion that generally no, it is not. At base, a full power thief will have a 7% increase in damage from the signets passive. The signet has a minimum recharge of 36 seconds. Having a 7% boost for that full duration is better than a 15% boost for only 5 attacks.

There is one exception. If you are running an ambush build and plan to burst down targets ASAP, then this signet is useful. Venomed Steal + Cloak and Dagger into backstab + heartseeker x 3 is enough to down other classes on occasion. The might from Signets of Power helps here, too. Even then, this is hit or miss, since so may players have been burst down by this tactic they carry skills to avoid it.