Just wanted to trow in my ideas of how to fix stacking:
The most problematic specialists seem to be Tycoons, Kings and Admirals. I think the reason why stacking them is so powerful is that they don't give you a debuff that stacks along with their abilities. Here are my ideas:
King - Reduces driller production by 25%, does not affect shields
Tycoon - reduces regular sub speed by 0.25
Admiral - reduces driller cap by 100
MoE - reduces all shields by 10, does not affect production
That would hopefully encourage players not to stack 2-4 of the same specialist, but it won't be impossible either.
About the sentry/princess/intel officer stacking, I thing it would be nice if the sobar range increase would be calculated in area and not radius. That way they wont stack exponentially.
“All warfare is based on deception. Hence, when we are able to attack, we must seem unable; when using our forces, we must appear inactive; when we are near, we must make the enemy believe we are far away.”
― Sun Tzu, The Art of War