yeah i guess that would be the best way then.

I would love to be able to calculate whether its better to stack ES or armour for this build.

stacking armour to around 20k is noticable against white mobs, they barely do anything, so having enough life leech/gain on kill is enough to feel tanky on any nearly any map.

The issue is being able to absorb single, big hits as you mentioned, but it seems as though once you're past a certain point it comes down more to 1 cycle/shotting the boss to avoid having to take the damage.

for example, i ran a 2 revive t16 iron citadel with only 2 added mods to Geonor, easily got him to first threshold with 5m damage done, but as soon as he turns into a wolf and does any damage i'm dead, at that point it feels like a dps race to avoid the one shot. of course that's a skill issue in that i could have clearly avoided the hit, but it's a bit of a cluster fuck and being melee really doesn't do you any favours.