Ok.... Headseeker only gives a bonus if you land a bodyshot; otherwise it is a wasted perk. To make the most of a perk like Headseeker you need a pulse rifle with moderate to medium-high stability, so that the pulse rises a small but significant amount over the duration of the pulse. Said another way: first shot lands in the body and the natural recoil of the gun pulls the other bullets into the head. The point of a max stability roll on Hopscotch is minimize recoil; if there isn't a lot of recoil, you have a very tightly (vertically) grouped pulse. Meaning at max stability most of the time... actually damn near all the time... your pulse will be all headshots, or all bodyshots. There is no mix of bodyshots and headshots so Headseeker is a mostly wasted perk. Reactive reload means a precision pulse of 3 shots delivers 150ish damage. It wont increase TTK in PvP on an enemy with full health but it will just about kill any guardian who has taken any kind of damage from just about any source. That is the point of Reactive Reload. Hidden Hand (on primary weapons at least) increases the precision hitbox, so you have a slightly larger target to land those 2 pulse kills. Anywhoo... its all a matter of preference. I wouldn't roll Headseeker though.