Let's take a stab at some comments/tips/opinions shall we?
MT + 2 OT. Hits moderately hard, frequently using his sabre lash attack which is applied across all 3 tanks. Sabre lash can be individually avoided by each of the tanks. Threat is wiped following bonestorm. Majority of damage is physical provided you don't stand in frost.
MT might consider including threat pieces to ensure smooth transition out of bonestorm. Also consider taunt glyph (or equivalent)
OT gear for max EH but once above a safe threshold, avoidance items may reduce healing load.
2+ MT according to strategy. Phase 1 tanking multiple fresh spawning adds, mix of physical and magical damage. Phase 2 transitioning to tank+spank with rotation between 2+ tanks forced by threat reduction debuff, weak melee with splash magic damage and high damage single target frostbolt that should be interrupted.
Enough HP to survive getting hit by a frost bolt (in case of accidents) and then threat (hit/exp) gear for good add control in P1
1 Tank for Saurfang with high EH and potentially some avoidance gear.
1 Tank for the boat, geared to pick up a series of adds spawning with fresh agro tables (hit/exp gear for control)
2 MT (assumes tank switching on Mark of Blood) rotating. Soft enrage at 35%. All damage physical.
Enough EH to comfortably survive the frenzy at 35%, then threat/avoidance gear as per personal preference/raid strategy. Consider glyph of taunt or equivalent.
2 MT forced to switch by Gastric Bloat. Boss self buffs by inhaling, hits very hard once fully buffed. Majority of damage is physical.
Max EH gear. Consider trinkets with controlled cooldowns for use in planned rotation. Equip alternate weapons/sigils/etc for use when not tanking but buffed with gastric bloat.
1 MT tanking boss, moderate hard hitter. No reason to tank switch, majority physical damage (some avoidable splash).
1 OT kiting adds (aside: not sure what stops a dps doing this)
Normal EH gear for both MT and OT. OT may consider glyphs/gear to assist ranged threat/taunt (e.g. hit, glyph of taunt or equiv) and possibly trinkets with controlled cooldowns.
(Speculating somewhat, not killed this in 25 man yet)
1 MT tanking boss until phase 3. Moderate physical hits with chance of some magic splash. High chance of healer interruption (forced movement).
2 OT tanking boss at 35%. Tank switch forced by Mutated Plague.
Max EH for the MT and Abom driving OT. OT 3 will be a third wheel in p1+2, consider compromise in gear to increase dps.
The kind of gear tuning I'm talking about isn't re-socketing all your gear for expertise or dodge... but I'm sure most tanks have a selection of trinkets in their bags, or a choice of weapons, or a spare set of gloves with armsman enchant, etc.