would you like to waste 10 arcane crystals just for that / do a few Griswold reruns in search for them if you are going to replace them in a few minutes anyway with the stuff you really need ? if yes , be my guest .
there is nothing mentioned before the Fiends because it makes no importance what you equip before that . be it rares or runewords or whatever else . you can get 2x Lum since mid/end act 2 . Also , with the benefits of increased XP from the /players 8 setting you can get to around character level 38 - 40 by that time , so i don't see where's the problem . if that is not reachable in MP it doesn't concern me , this is a SP compilation , therefore idc .
some random T1 tu-s won't make an important difference at that stage of the game since you're a caster . you could find better rares and save yourself the headake , i bet you can find some that can provide +1 to all skills too . you might consider 2x Shedim more usefull as they provide MaeK