The trick CK, is to add the emissive last.
First placed = First hit
Sucks, I know.
The emissive armor does all-or-nothing at the moment.
59 points of emissive vs a 60 damage CSM = 60 damage to the hull.
I know we had to press him to fix this in SE4, to make it work usefully, as it did in SE3. Such a pain to have to repeat the process.