I never use Awareness on my other tanks myself, even if I have it slotted. I guess I just never figured out the proper time to use it... and no situation has really called out to me as "Awareness Time." I'd rather have straight constant mitigation or ways to heal/bolster healing over preventing a chance at a crit. Then again, I don't raid or anything of that nature, so it might not be that big of a deal for me - and makes my five cross-skills easy to pick.
~