Summoner: Saffell's Frame - yes or no?

I just started a new summoner in Ambush and as in my Standard build i was using a Saffell's, i got myself one for the new character as well.

Now i have realised though that with the Saffell's and Purity of Elements Lvl 16, my minions only have 73% Allres, so the 4% Overcap are pretty useless currently. (Once i get my Purity to Lvl 19 this will of course be better but even with all the Increased Aura effect, i will probably still get to 77% or maybe 78% instead of the full 79%...)

Before i got the Saffells, i was using a rare shield that easily got my minions to the Res Cap at 75%.

Now my question:

Is the Spellblock from Saffell's worth losing 2% Allres or should i rather just stick to my rare shield until i get a higher level Purity of Elements?

Why not Rathpith globe for the 75/75 atk/spell block u can get with bone offering + skullhead.

75% ARes should be easy with just zombie base res and aura buffed purity