Yeah, for me the Legends one was easier to deal with because they at least had a character or two reference/recap it briefly in the series. Whereas with Millennium... It just felt like a big ol' printing error in which they left out a whole issue! Very frustrating, especially since there were real no hints that the impostor subplot I was referring to had anything to do with things outside the main story (though I sure did think it was weird that the Guardians popped up).
Thanks for the heads up on the orb!