I can't tell you precisely how much damage you're losing going with the 55 besides the fact that it is half as good haha
From my experience, as long as you have Yang's and a cubed coat or armor piece with rcr of any sort, you don't need anymore rcr or ihr in this case
I'd go with the vit one, besides it has more ias:D
The best setup is use the vit on this slot and get ad in other slots like gloves/shoulders
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