I would suggest full VIT, I have seen tanks live with 100-300 hp from a DS that would otherwise be a one shot on Twintania. Things happen and as you learn fights you may mistime your buffs, or be running from twister and not able to get that inner beast up for some reason. Yes, as you get more experienced with fights mistakes happen less and less, but that extra padding from VIT is quite nice to allow your SCH to land that Lustrate that will save you