1/18/2014 – tested +Boon Duration on two characters. Both characters (given below) yielded no additional +Boon Duration from Boon creating abilities/skills/etc.
First noticed on my 74 Guardian with 44% Boon Duration (24% from Virtues Trait and +20% from Runes) – ran through 3 Shouts and received no additional +Boon Duration.
Switched to test on my 80 Elementalist w/ 60% Boon Duration (30% from Arcane Trait and +30% from Runes) – swapped Attunements, used Auras, dropped Healing Rain. Not once received additional Boon Duration beyond the base level/amount provided in the Tool Tip.
I will continue to test, but current +Boon Duration from both Traits and Runes is broken!