We didn´t have that much time and just simply pitted Kols against a fleet of torpedo frigs.
As we were in this exercise only testing how the phase tech influences the damage done we didn´t use any of the Kols abilities (as it would add more random factors to the thing).
With the 6 phase techs researched (30% pass through) when the Kols shields broke down its HP was down by about 15% (numarically it should´ve been down by 20%, the 5% were repaired by the regen rate of the hull (The kol had no upgrades at all).
That means that every upgrade lowers the effective damage per time of your ships by 3% (18% after all 6 upgrades)
That means almost 1/5 of your shots are negated, and that even with the lowered shield mitigation rate.
This means in your example with unlimited shields, that means you need about 6,5 times the damage you normally would need to destroy the capship (Kol), meaning also 6 times longer.
Of course this is only a calculated number and does not take into account that the kol or anything else destroys your precious frigates or caps.
Personally i wouldn´t bother so much, because if you have 6 times the power to destroy the enemy you shouldn´t really bother with phase missiles either.
Torpedo Frigates are excellent capship killers, though
with just 60 cap of them and about 1.5 the cost of a capship you can kill a lvl1 Kol with only one loss.
