Well, I got my CNJ/WHM to lv50, and now I'm getting THM too, but I noticed a great difference between them:
THM IS DAMN FAST.
I know that there is a slight exp boost once you reach lv50 with a class, but it's still too much faster than CNJ.
I got 16 levels in 1-2 hours, by clearing the hunting log and grinding the FATE "Return of the King"!
With CNJ I had to play for a whole day between hunting log, FATEs, dungeons, leves and quests to get a single level up.
Is it normal?