I'm not sure if maybe I'm just doing it wrong, but I got this ship because I love Voyager, and I thought it'd cool to have the ablative armor, and I am a Science Officer.
It seems like more often than not, in PVP deploying the armor gets me killed rather than saving me in a pinch. When my shields go offline to deploy the armor, get killed almost instantly by whoever is attacking me, before the armor has a chance to even fully come on.
That being said ,I could deploy it earlier but if I still have shields and decent armor, I wouldn't particularly need to use it, at the time, so it's kind of like a waste of a fairly long cooldown, for 15 seconds of damage resistance that isn't even fully necessary.
I like the ship but so far the armor has been more of a disappointment.