It takes a bit, but WAR can solo them just fine without external heals. So long as you pick mobs that love to spam conal AoEs, you're barely getting hit.
Very bad idea.
Is already bad enough that players can go into it using "public airships" from ishgard. This should be a FC exclusive content through and through, maybe be matched with other FCs to get going.
I've never been to diadem. I don't even know how it works.
But any contents like the open world dungeons of FFXI and i'd spend most of my play time in that.
I'll keep hoping that's what Eureka is... though as with the PotD lockout, i am prepared to be disappointed.