PLD made things easier on learning healers throughout most of Midas and the first 3 raids from Creator. So yes, in most of that, PLD makes progression easier. Also A2.

I wouldn't really say WHM makes progression easier anymore, though. AST and SCH together have enough burst healing to make Cure III and Assize unnecessary in literally every dual-healer scenario, and as said before, Disable + CU are much better than WHM's powerheals.