The earcups on the edition 8s are slightly narrower than the sig djs, I have large ears and it was a fairly snug fit, like the sig DJs the edges of my ears rubbed a little on the inside of the cups. Comfort is ok but not amazing, ultimately I went with the sig djs due to it being cheaper, I wasn't prepared to drop that much money on the editon 8s for mediocre comfort.
You just have to stretch the headband out, I have a few boxes that I stretch the headphones over between listening sessions, i do it gradually over a few days changing the thickness accordingly.
i think that after some more reading, as edition 5 unlimited is bigger than edition 8, it should be just what i need!
i think that i would also buy signature dj anyways, because it has an amazing sound!