It's the holding aces and the other high damage perk that make hawkmoon such a beast. 2 headshots at normal damage and you're dead, 1 headshot if the perk procs. It's not a gun for spamming like you hear with the thorn. It's about getting 2/3 good shots with it very quickly. I had a few games with it the other night. When i was on song it was a beast, when i was aiming like a pleb it was useless.
Bottom line is, ttk is a great measure if you get shots on target where you want everytime. But if you can't use the gun like that reliably, then chances are something else will more likely float your boat (Oversoul Edict in my case)