Yeah, I usually target battle armor on the drop turn, as they are most vulnerable then--and mimetic makes that really hard. Transporting mimetic right up to the enemy is a great combo... the BA doesnt want to move much, so a cheap transport does the moving for them, and puts them into a really annoying position in front of the enemy.
BA as ambushers has never been my thing, and mimetic doesnt help that. Why pay for mimetic/stealth on a hidden unit? A cheap conventional infantry squad cant be picked up by active probes, and is cheaper and more damaging then mimetic BA. The mimetic BA, on the other hand, can trade shots efficiently out of hiding, that's what you pay for with the stealth bonus. Send the Meme squad up to the enemy gates and start blasting or spotting/Tag-ing without needing a special mission ability to have hidden units, enjoying a silly to-hit bonus in heavy woods while standing still in front of the enemy battle lines.