There was another debate on this topic a while back and it went all over the board with theories, scientific facts, real-world examples, Farraday suits, high voltage line repairs, etc.
The general gist is that there is more involved than "just" electricity. There is heat, impact, burns, shock, voltages, is the metal armour routing the charge to ground, padding under the metal armour, leather armour is thinner and perhaps offer less insulation, etc. A person in metal armour wouldn't want that armour resting on their body, there would be ample padding possibly protecting them from the voltage, but not the impact or heat.
I agree with @rdanhenry, -50 for the duration is worse than 6 rounds of stun.