It depends on what you want from it. If you want a pure full mage, then yes, all 3 food + the armor set will be eitr at least until your skills are so high that you don't need as much to use the staves and can cut back on either the armor or the foods and still play full mage (this at least > 50 in all magic skills, a tedious undertaking).

And as others said, hybrid works even better, at least for me.
I use 1 eitr food and don't use dead raiser generally (only when doing stupid stuff like cutting bulk wood where they keep the dwarves and necks and such under control). That is enough that I can use a staff as a no-ammo, stamina free bow yet still melee as well as ever (Ive replaced my stamina food with eitr, and since the staff doesn't use stamina and food doesn't change rate of stamina gain, its more or less a no-loss all gain change). The biggest drawback is the frost staff has poor accuracy so you need to get closer to small targets than you would with a bow. This is where the fire staff comes in, though, it can't miss.