Return of Reckoning

New Chosen with 2 questions:

1) is it worth (in pvp) to have negative chance to be crit therefore stacking Flawless armor and initiative/reduced chance to be crit?
I see some chosen running full ini talis and i have no idea if it's good to go like -15/-20% chance to be critted. how does it works ...

Title says it all: new player here pls i need a pve tank spec with mastery and renown for rr50.
Thank you all.