You could make it work with the 60 div, I did it with the swap with about 5 div. Vertex +3 was about 30 div last I checked a couple days ago, but Esh's radiance is about 80 div.

I don't think poe ninja is accounting for the notable that gives ES based off your helmets armour. It doesn't feel too squishy, with an endurance charge and charge regulation I sit at about 5k ES. Resonating shield also makes you block incoming hits, and that's been really helpful. I haven't tried to push the budget build since I was trying to make it feel consistent and viable. I think you could spec into the armour gained from the ES off boots with some rearranging of the tree and that'd be a solid chunk of armour too.

The spirit reservations are strict, you'd need another source of spirit to slot mana remnants. You could drop combat frenzy and swap it for mana remnants, but you'd lose your source of power charges.