Looks like staff gives you some extra 60 int, hit, lil haste....while the mace/shield gives you an extra red socket (so if you gem int its prob about the same including gem bonuses), half the hit but as spirit, and some crit.....plus like extra armor but prob not something to consider.
They are very close...esp when you consider the 60int on the staff is almost achievable with a int gem+set bonus which gives 50-60 int also......I would prob just stick with mace/shield and try to get the shield upgrade.....with power torrent wep chant and mighty int shield chant, prob similar SP/int either way but you end up with more crit.