I haven't played a WHM in T5 but I can't imagine it being more difficult than SCH. You have no Faerie to watch over, no Aetherflow to watch over, Adloquium needs to be up before a Death Sentence hits. Putting Sacred Soil and try to Succor before Fireballs. I believe the WHM is an "after-care" job while SCH is a "preventive" one.