I have doubts on the accuracy of the index pins. You only need a variation of around .4mm each plunge over your 80" to be out that much. Even if the pins are accurate using a bit to much lateral pressure could slightly bend the outriggers .4 of a mil easy.
Dont feel to sad
Most seem to dislike the out riggers. You are best to make a quick mark with a pencil. Below is how i mark mine out. Its simple but it suits me.
When i have a heap of boards and flipping them around to plunge i get confused
So i put the dot (usualy blue masking tape) on the left and that tells me what side to start with the Domis index pin. That first cut both sides is on the exact setting.
The X board tells me that is all plunged on the exact setting, and that is the side i insert the first row of Dominos.
The O side is the one i plunge on the next lateral setting. That makes for fool proof alignment.
Simple but i never have a problem joining the boards.
[Matty can you get rid of the second photo i accidently posted twice