Well, I don't know about Juggler. Personally, I still like Guardian, but the name is not that important.
Speaking of names. At this point, the Placate power would need a different name. Now it is basically Power Boost and the Placate is just a bonus. You don't have to get the aggro to use it. You use it on whoever you think you Might get aggro from, and then you buff or heal immediately. That's pretty effective I think, and would allow the AT to compete more effectively with defenders while not needing their damage to be punishingly low in order to be balanced, since the effect would not be permaable and damage, -res, and -regen don't benefit from Power Boost anyway.
I think we should obviously call it Power Placate.
EDIT: Added as an EDIT to the original post.