This belong to my experiment of using Prismatic elixir on raids. Without the elixir, but with aura or totem, you get 24.6% elemental damage reduction. With elixir, 32.7%. Orcanio did not use the elixir, everyone else did. The tank got 500K melee from fragments and 235K from the boss in P2. All the other damage was fire.
Let's calculate the unresisted fire damage. It's damage / 0.673 for everyone but Orcanio, damage / 0.754 for him and (damage - 735K)/0.673 for the tank. 11046K. Using resistance aura saves us from 2717 K damage. Using elixir saves us from further 894K. This was a 5 minutes fight, so 298 DPS/person was saved. Does it worth the DPS loss from missing flask? Questionable (please keep in mind that one can use 2 elixirs, so 275 spirit/mastery/crit/haste and the 298 DPS stands against the lost main stat).
However it's clear that the tank should use the resist and mastery combo all the time. This case just the resist part saved 465 incoming DPS on him, I can't calculate the melee damage reduction from mastery. I can't imagine a fight where the stamina flask would be better than resist and mastery.
While resist elixir + 275 secondary stat vs 300 primary stat is debatable, there is one thing that is not: resistance wrist enchant from leatherworking. The 70 resist saves 6.5% magic damage (assuming no elixir), and costs only 130 primary stat. It seems, LW is overpowered, especially for tanks.
Chris sent a perfect set of specimens.