The last time I remember using Flash was when I slotted it in for T10, then realized I can just stagger my BB instead and took it back out. Flash is ok in dungeons but I never even used it in those and got through 'em just fine, never had any aggro issues and I'd usually pull the whole floor if I could. I can understand those that like Flash as a safety net, though, and Ultimatum is relatively worthless so I can see that getting replaced (in a practical setting it's only good if you die mid-trash pull, get res'd, and need all the aggro back but you're better off just resetting at that point).
I read somewhere on here that RI + Awareness lets you parry from all sides in 4.0. I'm going to test it later to confirm, but if you're curious yourself just pull s/t -> RI + Awareness -> turn around.
