Like already said above, eye4eye is a good skill. Not exactly game changing, but certainly will make you a better WHM. C'mon, do some hunts log and challenge log with ARC, then turn to SCH when you hit ARC 30 so you can insta-queue for dgns for 4 more levels. TA-DA. Eye4eye: Useful for big mobs, since big mobs = more chances to proc and more enemies affected.

And, I think WHM have a very good time running main story. Cleric stance turn INT to MDN, so regen and pew pew pew. Sounds easy to me.
Run main story with dps is not hard. DRG got better defense and hp; ninjas are really powerful, but not exactly durable; brds can "forever-kite"; smn have a tank pet; black mage is powerful and can cross class phisyck. Monks... Well... can't hit positional soloing, plus are not durable. Maybe hard for them.