Damage-wise, Nature's Fury and Elemental Shroud only seem to do a little more damage than Spirit Dart, but I guess every little bit helps. ^^

I tend to use Nature's Fury as my main attack and haven't had any problems with stamina regeneration, but I usually alternate between other attacks and cures so I guess it depends on your battle style.

Nature's Fury has a pretty small area of effect so other targets need to be very near your main target. But the AoE is there so you need to be careful in congested areas or you might find yourself engaging more enemies than you intended. ><