Armor & Shields On Units...

[spoon]

Raging Deadstar said:
Shield Depleters Work on Fighters, Drones and Satellites
Shield Depleters Don't Seem to work on Weapons Platforms and Troops.

Shield depleters do work on troops, though not as shield-only damage (because troops can't have shield points). Instead, they deal regular damage -- which makes shield depleters the best weapon to equip your troops with, since they do the best damage. (though it could be argued that this is a bug, so using shield depleters on troops would be an exploit...)