what to use as Ring 2 as War?

[Gamemako]

It also decreases healing load, because your healers have more time to heal you, and can spend that time DPSing.

I think this is a key mistake. VIT does not reduce healing load except for a minimal increase to regen (40% of the amount increased per minute). You do not get back anything from a static HP pool -- the healer has to put just as much HP back in whether you have 5000 or 10000 HP. The amount healed is dependent upon enemy damage, not player HP. By contrast, higher mitigation (e.g. higher parry) reduces total healing load by making a portion of that healing requirement disappear. That means that using Gryphonskin will require less healing time and MP on average even before considering faster clear times. Normal combat is always subject to RNG. This isn't really important to discuss at all: barring the small portion of the time you have Awareness, you can always have enemies randomly crit the heck out of you and make your healer turn around and spamheal to undo it.

//EDIT: I'm not saying one way or the other what the person should take. As far as ilvl70 stuff goes, HQ Gryphonskin is the obvious winner, but when you look at ilvl90 stuff, you have to determine whether you can even afford to lose that HP, and I just don't really have any reasonable way of modeling that as it depends on specific encounters.