Warriors Viable?

[TouchandFeel]

Either tank is perfectly viable and capable as MT or OT for almost all the content with the only exceptions being some level of preference in the more hardcore content like Coils, but in those cases most groups will want one of each.

WAR doesn't or at least shouldn't create more stress for the healer since they pretty much both require the same amount of healing in the end. A WAR can take more damage per hit than a PLD but they also get more HP back per heal. This leads to bigger numbers going in (heals) and bigger numbers going out (damage taken) and these can cause some healers to freak out a bit and over heal.

Really which tank is best depends on personal preference and play style. Level up both to 50 and see which you like more. Also leveling up the other tank class will unlock cross-class skills that you will definitely need.

Lastly, you shouldn't expect to be the MT or OT all the time and should just get comfortable being able to be both since it is pretty much a guarantee that you will end up having to play both depending on the situation.