Souls is nice because it mitigates damage while you have protection prayers on, potentially more than a BN would heal depending on how much damage you are taking.
Pretty sure that spirit shields are still the *hardest* shields to get in this game. In reality though, all of my friends are using t90 shields for tanking the new raid bosses anyway.
Barrows shields are still better in situations where you are using your shield to heal yourself instead of tanking damage (eg. Araxxor, Vorago Base, Nex)
What are you risking at Vorago lol? Just protect your weapon(s), boots, and shield. If you can't get back to the grave in 3 minutes, you've got serious issues.
General must haves for general bossing: 99 in all combats (attack/magic/ranged/strength/hp/defense) 96 summoning Full superior (elite) void Magic + Ranged Surgeon's Asylum Ring of Vigour T80 Nex Boots / Silverhawk Boots / t90 Power Boots Things you will need for Nex solos: Sirenic Armor (will probably have a few pieces by the time you get a crossbow) Ascension Crossbow(s) OR Noxious Longbow Seriously though, the Nex armors are really not worth going for outside of the boots which are basically outclassed by the new t90 power boots. I would suggest getting your Ascension Crossbow and camping Araxxor for a Noxious Staff and/or Noxious Scythe.