i had full blue +4&5 light armor for my 78 wizzard, it couldnt nuke so hard (cuz of low mag reinforce) and it still got pwnd by snipers (2 hit by party sniper altho i had 10k hp) mostly cuz of potion delay. I would survive pretty long when i had vigors , but once they run out you get pwn if you dont oneshot it. Once i deleveled my cleric and maxed my wizard skills and wore robe i just wtfpwn any damn mob ( except for mages , theyre still 2 high 4 me). Snipers and hunters still hit me but since i oneshot 5 at same time with ground nuke i got no problem with wearing robes. I even can take on hunter giants now cuz i keep statuses one em all the time (still pwns me without vigors

).
so, if you wanna get your wizzy decently to 90 , dont waste SP on cleric and go full wizzard to 90 and then just farm for cleric skills.
Light armor from my expirience is not good choice altho all theory says its gonna give you some survivability.