BL vs EoW on miner

First off, I play only Hardcore. So I cannot invest everything in damage and have to make choice.

The second. I want to know how my DPS is calculated properly. For example in case of Ball Lightning the DPS per Ball is calculated this way:

Average Hit * 6.6667 = DPS

BL hit rate is completely independent from cast speed and it has fixed delay 150 milliseconds.

But when you're fighting with strong mobs like metamorphs or any other moving enemies, BL's effectivity goes down significantly because it cannot change direction after mines were detonated.

On the other hand, Eye of Winter fires 8 projectiles but Skill Gem doesn't have clear description how often it happens and the EoW can autotarget enemy after mine was detonated allowing to stack 20+ EoWs way more reliably on the moving targets.

Obviously I have to multiply Average Damage on Amount of Projectiles hitting the target but I do not know how many projectiles hit the target and how often they recharge.

1. Can someone give me clear explanation how to calculate EoW DPS correcly
2. From your experience is it worth to switch to BL in late game to shotgun bosses playing Miner?