- Stand at the Mayor in Act 3, run to the front gate, and observe distance traveled at last skill's expiration. I picked this location because if you stack all three you can just barely make it out the gate before the Chicken drops. In principle, all the skills should increase distance traveled by a roughly equivalent amount - though you do have to adjust for the longer duration of AC.
Skills: Spirit Walk/Jaunt, Horrify/Stalker/, Hex/Angry Chicken. Results for movement traveled when stacking two or more skills are as follows:
Stack all three: out gate
Stack SW/AC: tiny bit short of gate
Stack SW/Horrify: side edge of campfire
Stack Horrify/AC: just past campfire
One theory is that Horrify isn't actually stacking past the movement speed cap on gear, even though the tooltip says it is. Further testing with a different Spirit Walk rune (reducing the variance on the SW vs. AC/Horrify treatments) gives results that aren't consistent with this.