its a tossup, right now I'm 25blm/9whm and I have like 260hp/320mp
the high MP is great for long fights, but when something particularly nasty hits me for 90+ dmg in one swing.....or even worse a giant's special attack for 180, it really really hurts
If you have a party with good provokers its great....otherwise it wouldn't be a bad idea to carry some mp->hp conversion rings