I'd like to see Shield Shunt as an "armor for damage reduction calculation only" so that not only low-tech ships can use it.
If I'm not wrong, this kind of armor it's additive with "residual armor", so its good at making hull stronger.
As example I'll give this idea of Shield Shunt +20/30/40/50 armor for damage reduction calculation only:
Let's say you want to use Sunder with this shield shunt so it can act more aggressive (Sunder has 1.2 Shield flux/damage anyway...)
Normally Sunder has only 12.5 residual armor (5% of max armor[250]), it would receive 89 damage from every Thumper Bullet( 100/112.5 = 0.8888 * 100 = 89).
With this Shield Shunt it has 42.5 residual armor (5% of max armor + 30), it would receive 70 damage from every Thumper Bullet( 100/142.5 = 0.7 * 100 = 70).
This Sunder is still fragile, but it will survive a little more hits to the hull while having the benefits of being more aggressive, not caring about overloading and trying to dodge more shoots (shieldless ships tend to dodge more bullets).
While this does not look amazing at first, this version of Shield Shunt benefit almost every ship, if your ship has low armor you can always stack "Hull integrity" and/or use an officer with Damage Control or an officerless ship if you have the "Support Doctrine" skill.
And for Low-tech Ships... they have good Armor and Hull stats already so it will benefit them good.