Pulmonary impact in my experience is really destructive as long as you run enough things to trigger it. I trigger it with fist flurry (into Palm Strike, it adds a 3rd stack when interrupting). Kick from bandit's defense. Each hit on the Impact Strike chain can also trigger it, although if you're hitting a single target, only one will actually trigger it (the one that interrupts). You can also have some interesting effects with shortbow #4's interrupt + pulmonary. I think it's very good, personally.
Staff master is also quite good, but I don't use a staff, and I have no endurance problems with dagger + dagger and don't need the endurance per initiative spent. I do have three thieves and two are daredevils - one is a staff thief, and he uses staff master. He's a very dodgy/defensive-ish build though, whereas my main thief is a mix of sustain/dodging and burst damage. The other is a Deadeye and is an overall offense build with a gunslingery theme, usually with pistol+pistol and rifle. Rifle is up while damage is the pure focus, pistol + pistol when it's time to move and survive and sustain (pistol spam + signet + keep moving is very good for sustain, EVEN MORE SO with piercing shots, which I kinda swap on and off depending on the situation leading into a fight)