Team VIT exists because how dire the situation with WAR is. It's a mathematically-inferior tank right now, but it is in practice much worse with how WAR gets burst-instagibbed. On a continuous basis, STR is more efficient in terms of healing, mitigation, and damage; if you're farming easier dungeons, you're certainly better off going pure STR. However, when you hit Titan HM and BC, WAR gets rocked so hard that I can see how VIT would be preferred. 'Course, the true efficient solution to that endgame content is not to bring WAR at all...