I don't know what to think about KG. Now it would be awesome if this would be the 'better' Battle Chant in terms of removing debuffs, but I don't really think it has many uses in WoE as it disables all you party members (or most of them anyway...). It would be interesting if it could be used to have a 5 second period of not being able to be targeted at all from Chasers, but if you KG and there is a Chaser around, you're an easy target after all.
And the Debuffs it removes, are not really worth it: there is a quick counter to any of those really. While it removes it from your party members too it's maybe nice to have at Lv1 ? But I heard there is a CHANCE to remove the debuffs? (See Almr's post) Then it might not even be worth it at Lv1.
All I'm speaking off is for WoE! I know from Chakri that this Skill is actually pretty usefull in a PvM environment. I guess it will take a few WoE to test this skill and decidide it's usefullness.