How are they? Do you notice a difference?

I've been using the +40 armor one, but my armor is already so high that I don't really notice anything

remember, in the amt of time needed to cast stone then switch over to a combat spell and cast that, u could have just spammed the combat spell right away and killed the enemy faster.

as a mage wearing the novice robes and hood though, stone makes a HUGE difference when fighting a "boss".