Maybe it's because all my mage experience is on softcore, but i used to go with 25 vitality, and now i go 20 vitality, and i rarely see monsters do more than 600-700 to me.

My gear would probably fit in the mediocre-godly range, but if i had the exact same gear on HC i don't think i would go more than 30 vitality, not since paul added heal charms.