I haven't really argued in my previous answer, so here we go.
SCH is better for dps in my opinion. You have a 150 potency dps skill not in gcd that regain some mp and instant, many dots (two without accuracy requirement), Ruin II (instant dps skill) when you have to avoid mechanics/just after broil/etc, and you can stay in cleric stance longer with your fairy, + all the emergency skills allow better cleric stance dance.
I think WHM is better as main healer (even if he can use some dps skills though) and SCH as healer-dps support during progression (in fact, if you play with a good whitemage, all the time).
When I see a WHM that dps and letting me heal everything through a fight, when I play my SCH, I find it weird. But it's just my opinion.
