I had 1200 TEN for a week 1 clear on Neo at i320 (as Warrior). Properly managing defensive cooldowns is significantly more important than tenacity for this tier. I can't speak for the upcoming Super Savage encounters or future tiers, but for current content, it almost doesn't matter. Neo ExDeath doesn't even have any auto attacks, so any hits you take as a tank are either intended to be tank busters, or it's raid wide damage. Tenacity isn't even a player in that fight. By all means, if you plan on doing Super Savage content, take the tenacity equips as they drop and put them on retainer, but my personal BiS for current savages will only have ~750 TEN.