Through my own testing I've found 30 MND to be cause my heals to range from 650-680. With 30 VIT I heal for 620-650. The only reason I'm specced VIT though is because I don't hit the 4.1k HP threshold required for T5. However, even with 30 VIT I've cleared T1-T4 easily and haven't had trouble healing T5 yet.