I guess both job doesn't have the mp issue if played right. SMN wise for ruin2 it heavy mp consumption but still manageable you might not end the dungeon with full MP but you still end it with a little mp left. In lv 50 content I usually find myself use less ruin/ruin2 but more AoE staff like bizzard2 and still keep a good chank of mp with AF so, don't be to conserved with your skill put them out and see what it happen!