1. Yes, but it seems to happen more times than not. even then, 3 shots from last word is only slightly slower than Thorn.(just as fast if you count the time for the target to die from the DoT. 2. With thorn I find its faster to just hit them 3 times(even with 2 headshots) Because the dots give them an extra second or so to kill you if you don't fire the third shot. Obviously if you can fire 2 and go behind cover thats better, but not always the case. 3. I still think in the vex's respective range its 100% better, If you have a vex and stick to short-mid engagements I feel you're better off than a thorn in the same situation.